Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Cartilage and Bone
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
SEM of trabecular/cancellous bone. Inserm.
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives
Cartilage and Bone 1.
Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth
2. 3.
4.
d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
5.
Cartilage is a specialized type of solid connective tissue which, along with bone, is distinguished by the relative rigidity of its extracellular matrix (ECM); it is easily distinguishable from bone by its avascularity; it provides flexible support to tissues (e.g., ear, nose, larynx).
Types of cartilage (hyaline, elastic, and fibrocartilage) are distinguished by the characteristics of their respective ECM (e.g., the dominant type of fiber).
Bone is a specialized type of solid connective tissue characterized by a mineralized ECM that stores calcium and phosphate. Woven bone (immature) differs from lamellar bone (mature) in its collagen fiber arrangement; all new bone is woven, but it becomes remodeled into lamellar bone, with few exceptions.
Lamellar bone has organized ECM sheets (lamellae); the dense bone that forms the outer cortex of most bones of the body is referred to as cortical bone; while the lessdense, inner bone which is not as compacted but instead arranged in a lattice-like configuration is referred to as cancellous bone.
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline
Bone Formation and Joints 1.
2. Elastic
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
a.
b.
3. Fibrocartilage
B. Bone
Bone formation occurs via two basic mechanisms:
2. 3.
Intramembranous ossification forms bone within mesenchyme (“membrane”).
Endochondral ossification forms bone by replacing a cartilage model.
Regardless of the mechanism, all new bone is woven bone which is remodeled into lamellar bone (either compact or trabecular), with organized sheets of bone (lamellae), by osteoclast and osteoblast activity. Joints are places where bones meet (articulate), allowing at least the potential of bending or movement; examples include synovial joints (diarthrosis) and intervertebral joints.
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Learning Objectives I – Cartilage and Bone 1. Understand the variations in structure and function of the three major types of cartilage, with regard to both the cellular and extracellular elements. 2. Understand the key ultrastructural features of the chondroblast and how they relate to function. 3. Understand the structural features and functions of osteogenic cells: osteoblasts, osteocytes, and osteoclasts.
4. Know the major differences in structure and function between woven and lamellar bone, and between compact and cancellous bone. 5. Understand the structure and composition of an osteon and how it is formed.
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Learning Objectives II – Bone Formation and Joints 1. Understand the differences and similarities between intramembranous and endochondral bone formation and the key function of the periosteum in bone growth.
2. Understand the organization of the epiphyseal growth plate and its role in endochondral bone formation and growth of long bones. 3. Understand the structure of a typical synovial joint, including the nature and functions of the synovium.
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Keywords Articular cartilage Bone Canaliculi Cancellous bone Cartilage Central (Haversian) canal Chondroblasts Chondrocytes Compact bone Elastic cartilage Endochondral ossification Endosteum Fibrocartilage Growth plate Haversian system Howship’s lacunae Hyaline cartilage Intervertebral joint Interstitial lamellae Intramembranous ossification Joint
Lacunae Lamellae Lamellar bone Marrow Osteoblast Osteoclasts Osteocyte Osteoid Osteon Perforating (Volkmann’s) canal Perichondrium Periosteum Synovial joint Synovium Trabeculae Woven bone Zone of calcification Zone of hypertrophy Zone of osteogenesis Zone of proliferation Zone of reserve cartilage
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth
Slide 2: Trachea, Trichrome
thyroid gland perichondrium
look here for hyaline cartilage
d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
what kind of epithelium lines the lumen of the trachea?
lumen
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
Slide 2: Trachea, Trichrome hyaline cartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
perichondrium peri = “around” chondrium = “cartilage” hyaline (Gr. “glassy”) cartilage is the most common type of cartilage in the body; it contains the smallest proportion of fibers in the ECM (primarily type II collagen), giving it a fairly homogenous, glassy appearance
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
Slide 2: Trachea, Trichrome
perichondrium fibroblast
chondroblast chondrocyte
hyaline cartilage notice the lack of vasculature within the cartilage; it relies on diffusion from vessels in the perichondrium, limiting the maximal cartilage thickness
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
perichondrium is dense regular CT essential for appositional growth and maintenance of cartilage; it consists largely of type I collagen, fibroblasts, and progenitor cells for chondroblasts that divide and differentiate into chondrocytes; hyaline cartilage is three-dimensionally surrounded by perichondrium, expect as articular cartilage in joints; elastic cartilage also has perichondrium, but fibrocartilage does not
Labs 6/7 – Cartilage and Bone IUSM – 2016
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints
1. Synovial
2. Intervertebral
Summary
chondrocyte (cell) located in lacuna (space) chondroblast
perichondrium
1. Hyaline 2. Elastic
V.
Slide 2: Trachea, Trichrome
hyaline cartilage
I.
fibroblast appositional growth occurs at the interface of the perichondrium and the cartilage as chondroblasts, from perichondrial cells, actively synthesize new cartilage matrix; they secrete ECM components until they encase themselves within the matrix – the small remaining, matrix-free space that the cell inhabits is called a lacuna (Lt. “little lake”); once encased, the cells are referred to as chondrocytes, which continue to synthesize and maintain ECM components; both types of cells have basophilic cytoplasm rich in rER for collagen synthesis terminology note: the suffix –blast identifies immature, not fully-differentiated cell types; those cells differentiate into mature, terminal cells identified by the suffix –cyte; fibroblasts are a slight exception to this rule, as the term fibrocyte is seldom used and has been newly applied to types of circulating mesenchymal progenitor cells
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide 140: Trachea, H&E
Learning Objectives Keywords
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
the empty appearance of some lacunae is an artifact of slide preparation, as the cells either pull away from the matrix or are lost
hyaline cartilage
a. Intramembranous formation
perichondrium
A. Cartilage
small clusters of chondrocytes are referred to as isogenous groups and reflect interstitial growth
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
lighter-staining interterritorial matrix is located between groups of chondrocytes and reflects concentration differences in ECM components
darker-staining territorial matrix surrounds isogenous groups
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
Slide 87: Epiglottis, Masson AF
elastic cartilage
perichondrium lamina propria (loose CT) non-keratinzed stratified squamous epithelium
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
the epiglottis (protects entrance to larynx) consists of a core of elastic cartilage surrounded by loose CT and a covering of stratified squamous epithelium; elastic cartilage is similar to hyaline cartilage except that it contains an abundant network of elastic fibers in addition to type II collagen; visualization of the elastic fibers usually requires special stains; it is found in the auricle of the ear, walls of the external auditory canals (auditory meatus), auditory (Eustachian) tubes, epiglottis, and cartilages in the larynx
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide 56: Elastic Cartilage, AF
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
perichondrium elastic cartilage
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
the separation of the tissue is an artifact of slide preparation
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide 25: Auditory Meatus, H&E Slide Overview
Learning Objectives Keywords
A. Cartilage
2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
skin
1. Hyaline
keratinized stratified squamous epithelium hair follicle
sebaceous gland
ceruminous (earwax) gland perichondrium
elastic cartilage
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
distinguishing elastic cartilage from hyaline cartilage can be tricky in H&E without specialized stains to show the elastic fibers; however: the elastic fibers provide a more heterogeneous appearance to the cartilage vs. the smooth, glassy appearance of hyaline; elastic cartilage has a greater density of chondrocytes with less ECM between them than in hyaline; and the chondrocytes in elastic cartilage tend to be larger than in hyaline
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
Slide Overview
tendon
skeletal muscle periosteum
cortical bone
bone marrow within trabecular bone adipocytes
c. Appositional growth
endochondral ossification
a. Woven
skeletal muscle
d. Internal remodeling
3. Types
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
Slide 131: Fibrocartilage, H&E
1. Synovial
2. Intervertebral
Summary
adipocytes
attachment of muscle to the bone the slide shows the pubic symphysis, which is the cartilaginous joint linking the pubic bones of the pelvic girdle; beyond the fibrocartilage, examples of many other tissue types and structures can be identified
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 131: Fibrocartilage, H&E
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
chondrocyte in lacuna collagen bundle
fibroblast
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
fibrocartilage is a combination of dense regular CT (type I collagen) and hyaline cartilage (type II collagen); the collagen bundles and chondrocytes are generally arranged in rows parallel to the direction of functional stress; unlike hyaline and elastic cartilage, there is no distinct surrounding perichondrium in fibrocartilage; it is found in intervertebral discs, attachments of certain ligaments, and in the pubic symphysis
Slide 34: Bone, H&E
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide Overview
Learning Objectives Keywords
callus
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
1
cortical bone
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
fracture
c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
2
hyaline cartilage
EC Oss trabecular bone
sections (1) and (2) are two rib segments from a fetal/newborn rabbit; (1) gives an example of a bone fracture and repair processes (the callus is a temporary formation of highly proliferative fibroblasts and chondroblasts extending from the periosteum down into the fracture to form new bone); (2) gives an example of endochondral ossification (EC Oss) bone growth
Slide 34: Bone, H&E
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide Overview
Learning Objectives Keywords
P
A. Cartilage
Act P
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
HC
1. General Overview
2. Formation and Growth
Wb
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
M M
Tb
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
from the outside: (P) is periosteum, the dense connective tissue surrounding bone, with clearly visible collagen bundles; (Act P) is an area of more active periosteum with lots of cellular differentiation occurring; (Wb) is woven or primary bone; (HC) are areas of hyaline cartilage; (M) is marrow with abundant blood cells; (Tb) is mature, lamellar trabecular bone; close examination shows endosteum on the edge of the bone bordering the marrow
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Slide 34: Bone, H&E Slide Overview
P
A. Cartilage
1. Hyaline
Cb
M
2. Elastic
3. Fibrocartilage
B. Bone
Tb
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
Tb
Wb
P
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
from the outside (top): (P) is periosteum with clearly visible collagen bundles; (Cb) is cortical bone with a lamellar arrangement of bone matrix and osteons; (M) is marrow with abundant blood cells; (Tb) is trabecular bone with endosteum on the edge of the bone bordering the marrow; (Wb) is woven or primary bone which is newly-formed bone with an irregular arrangement of collagen fibers (i.e., not lamellar)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
Slide 34: Bone, H&E Slide Overview
periosteum (dense regular CT) peri = “around” osteum = “bone” fibroblast
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
osteoprogenitor cells (osteoblasts) osteocyte in lacuna
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
periosteum is dense regular CT that surrounds the outer surfaces of bone (except at articulations) and attaches to the outer lamellae via collagenous Sharpey’s fibers (not always seen); it contains osteoprogenitor cells which are capable of differentiating into osteoblasts and forming new bone (appositional growth); blood vessels pass between the periosteum and bone through perforating (Volkmann’s) canals, with most blood directionally flowing from the marrow cavities and draining out through periosteal veins
Labs 6/7 – Cartilage and Bone
I.
Introduction
IV.
Slides
II.
III.
Slide 34: Bone, H&E
IUSM – 2016
Slide Overview
Learning Objectives Keywords
trabecular bone
A. Cartilage
1. Hyaline 2. Elastic
B. Bone
1. General Overview
how new blood cells leave the marrow
2. Formation and Growth
c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
hematopoietic cord
marrow-filled cavity
b. Endochondral formation
stroma of bone marrow
red blood cells in vascular sinusoid
3. Fibrocartilage
a. Intramembranous formation
endosteum
where blood cell development occurs endosteum trabecular bone
osteocyte (cell) in lacuna (space)
endosteum lines all the internal surfaces of bone (marrow cavities, osteons, and perforating canals); it is generally only a single cell-layer thick and consists of osteoblasts and bone-lining cells; inactive osteoblasts and bone-lining cells are generally flattened with only dark, elongated nuclei being visible; osteoblasts that are actively secreting bone ECM components are much more round or cuboidal in appearance
Labs 6/7 – Cartilage and Bone
I.
Introduction
IV.
Slides
II.
III.
Slide 34: Bone, H&E
IUSM – 2016
Slide Overview
Learning Objectives Keywords
marrow
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
endosteum with osteoblasts (round, plump cells)
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation
osteoid lighter-stained area between endosteum and mature bone
b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
trabecular bone
osteocyte in lacuna
osteoid is the collagen-rich, non-mineralized precursor to true bone ECM; it is secreted by osteoblasts, such as those of the endosteum, during bone growth, repair, and remodeling; the osteoblasts subsequently calcify the osteoid into hard bone matrix, and in the process, they become trapped in the matrix (in lacunae) and become osteocytes (similar to the process of chondroblasts becoming chondrocytes in cartilage)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 34: Bone, H&E Slide Overview
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
osteoclast within Howship’s lacuna
osteoclast within Howship’s lacuna
osteoclasts (Gr. “bone breaking”) are large, acidophilic, multinucleated cells (generally 5-20 nuclei); they are critical for bone remodeling and resorb bone by secreting organic acids which dissolve hydroxyapatite and lysosomal enzymes which break down the osteoid matrix; at the bone surface, osteoclasts are found within surface depressions caused by the resorption of bone called Howship's lacunae (or resorption bays)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Intramembranous Ossification
1. Primary center of ossification: mesenchyme cells osteoblasts
2. Osteoblasts begin depositing bone matrix to form trabeculae or spicules of woven bone (immature bone) extending radially from the ossification center; osteoblasts become osteocytes 3. Marrow develops in spaces between trabeculae
4. Periosteum and endosteum develop from mesenchyme membrane on surfaces of new bone 5. Woven bone is remodeled to form lamellar bone (compact and trabecular)
Labs 6/7 – Cartilage and Bone
I.
Introduction
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Slides
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Slide 130: Fetal Skull
IUSM – 2016
Slide Overview
Learning Objectives Keywords
A. Cartilage
1. Hyaline
a. Intramembranous formation
nasal cavity with cartilaginous nasal septum in the middle; surrounded by intramembranous bone development of the skull
d. Internal remodeling
tongue in the oral cavity
2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
b. Endochondral formation c. Appositional growth
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Side View
developing tooth with surrounding intramembranous bone development of the jaw
Frontal View
see Slide 12a (464) and Slide 32 (NW) for additional examples
Slide 130 – Fetal Skull
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
Slide 130: Fetal Skull
1. Synovial
2. Intervertebral
Summary
trabeculae (or spiculae) of new woven bone are dispersed within mesenchyme
look for osteoblasts on the surfaces of the bone, while osteocytes can be seen contained within the lacunae of the bone mesenchyme (primitive CT)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
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III.
Slide 130: Fetal Skull
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
trabeculae of woven bone (new bone)
periosteum (dense CT)
specialized olfactory epithelium
hyaline cartilage
mesenchyme
even though hyaline cartilage is present adjacent to the mesenchyme, it is not involved in the formation of the new bone seen occurring here via intramembranous ossification (not endochondral ossification)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Endochondral Ossification
Unlike in intramembranous bone formation, endochondral ossification occurs when a hyaline cartilage model is replaced with bone; this more complex method of bone formation provides the benefit of having a load-bearing structure in place (cartilage) before the bone has formed; the bones of the extremities and load-bearing bones of the axial skeleton (e.g., vertebrae) are formed via this method, which can be spatiotemporally separated into the following zones:
1. Zone of Reserve Cartilage: hyaline cartilage acts as source of cartilage to undergo ossification 2. Zone of Proliferation: normal chondrocytes multiply
3. Zone of Hypertrophy: chondrocytes enlarge and align
4. Zone of Calcification:* cartilage matrix calcifies providing scaffold for new bone; chondrocyte degenerate (apoptosis) 5. Zone of Ossification and Resorption:* osteoblasts invade and bone is deposited on the calcified matrix; osteoclasts begin the remodeling process
Note: Because the rates of chondrocyte proliferation (in zone of proliferation) and destruction (in zone of calcification) are approximately equal, the epiphyseal plate does not change in thickness; instead, it is “displaced” away from the middle of the diaphysis, resulting in growth in length of the bone.
Labs 6/7 – Cartilage and Bone
I.
Introduction
IV.
Slides
II.
III.
Slide 34: Bone, H&E
IUSM – 2016
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth
hyaline cartilage
look here to see endochondral ossification
marrow woven bone
d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
epiphysis (end of bone)
epiphyseal growth plate
diaphysis (shaft of bone)
Labs 6/7 – Cartilage and Bone
I.
Introduction
IV.
Slides
II.
III.
Slide 34: Bone, H&E
IUSM – 2016
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
zone of reserve cartilage typical hyaline cartilage
zone of proliferation chondrocytes form rows or clusters of cells from successive mitotic divisions
zone of hypertrophy
zones of calcification & ossification
chondrocytes greatly enlarge in size
matrix becomes calcified chondrocytes degenerate osteogenic cells and vessels invade from the bone marrow osteoblasts form new bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Slide 13 (464): Foot, H&E
Slide 15a (464): Joint
Slide 13a (464): Bone, H&E
Slide 42a (464): Fingertip
primary ossification centers
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact i. Cortical/Compact
ii. Cancellous/Trabecular
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
Slide 34: Bone, H&E
marrow
endosteum bone
osteoid (pale-staining) osteoblasts
periosteum (dense CT)
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
while endochondral ossification provides a means for bones to lengthen at the epiphyseal growth plate, bones grow wider (increase in diameter) via appositional growth at the interface between the bone and the surrounding periosteum; osteoblasts differentiate from precursor cells and laydown new bone matrix (osteoid) onto the surface of the bone, increasing the overall width; the marrow cavity then also enlarges by resorption of bone on the endosteal surface
Labs 6/7 – Cartilage and Bone
I.
Introduction
IV.
Slides
II.
III.
Slide 104: Bone, H&E
IUSM – 2016
Learning Objectives
periosteum
Keywords
A. Cartilage
cortical bone
1. Hyaline 2. Elastic
resorption canal
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation
osteon
d. Internal remodeling
central canal
b. Endochondral formation c. Appositional growth
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
marrow
during internal remodeling of bone, osteoclasts invade a section of compact bone and resorb enough bone to create large resorption canals (often irregularly shaped borders with the dimensions of a new osteon); into this newly created tunnel, blood vessels and osteoprogenitor cells enter; osteoblasts begin to deposit new bone along the wall of the tunnel, forming lamellae (Lt. “thin plates”) of new bone; synthesis of new bone continues from the periphery to the center of the canal, with concentric layers (rings) of new bone being deposited until only the small central canal of the osteon remains with the neurovascular bundle at the center
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 13a (464): Developing Bone, H&E
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
woven bone
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
new bone, regardless of the process of its formation (e.g., intramembranous or endochondral formation) is considered immature due to its lack of organization of its bone matrix (it is non-lamellar bone); because of the random arrangement of the osteocytes and the interspersed haphazard collagen fiber arrangement, new bone is referred to as woven bone; woven bone will be remodeled into cortical bone and trabecular bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide 12 (464): Decalcified Bone, H&E
Learning Objectives Keywords
A. Cartilage
endosteum
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
resorption canal
arrangement of parallel lamellae of bone matrix osteocyte in lacuna
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
new woven bone is generally soon remodeled into lamellar bone which is named due to its distinctive lamellated architecture with parallel layers of sheets (lamellae) of bone matrix, as opposed to the haphazard, disorganized matrix arrangement of woven bone; both cancellous/trabecular/spongy and cortical/compact bone are types of lamellar bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
Slide 104: Bone, H&E periosteum
cortical bone
marrow (with lots of adipocytes) a trabecula of cancellous bone (Lt. “lattice”)
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
cancellous/trabecular/spongy bone is the “sponge-like” network of lamellar bone which extends from the peripheral cortical bone and fills the interior of bones; it consists of a series of interconnected trabeculae (Lt. “beam/timber”) composed of lamellae of bone matrix; the spaces between the trabeculae are continuous and filled with marrow; unlike the marrow shown above, most bones of the body are filled with yellow marrow which is primarily adipose tissue
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 12 (464): Decalcified Bone, H&E cortical bone
marrow
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
skeletal muscle
periosteum
central canal of osteon
resorption canal
osteocyte
cortical/compact bone is the compact, dense layer of bone tissue found at the periphery (cortex) of bones; it is largely composed of osteons (or Haversian systems) – functional units – which consist of concentric sheets (lamellae) of bone matrix surrounding a central canal (or osteonal/Haversian canal), which contains the blood vessels and nerves that supply the osteon; osteon organization is generally only seen in cortical bone, but it may be seen in large trabeculae of spongy bone; the overall architecture is best observed in ground bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 32: Ground Bone
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
look here to see osteons in cross-section (transverse)
look here to see osteons in longitudinal section
unlike the previous slides of bone which were chemically decalcified in order to permit them to be sectioned normally like other tissues, ground bone is not fixed but simply allowed to dry and then ground into thin sections; while most of the cells and tissue are lost, this method keeps the calcified bone matrix intact and permits better appreciation of the bone architecture, especially of the osteons of compact bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Slide 32: Ground Bone
Learning Objectives Keywords
Transverse Section
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
central canals
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
outline of 2 osteons
Labs 6/7 – Cartilage and Bone
I.
Introduction
IV.
Slides
II.
III.
Slide 32: Ground Bone
IUSM – 2016
Transverse Section
Learning Objectives Keywords
A. Cartilage
interstitial lamellae
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation
lamella (sheet) of bone matrix
central canal
b. Endochondral formation
canaliculi (faint lines)
c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
lacunae (spaces)
within each osteon, the concentric lamellae of bone matrix are clearly visible; lacunae, which in living bone contain osteocytes, occur between the lamellae; from the lacunae, canaliculi (Lt. “small channels”) radiate through the lamellae connecting the osteocytes together and to the central canal (with neurovascular bundle); interstitial lamellae are remnants of osteons that have been partially resorbed during bone remodeling
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 32: Ground Bone Transverse Section
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
perforating (Volkmann’s) canals
c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
perforating (Volkmann’s) canals generally run perpendicular to osteons and provide links between individual central (haversian) canals; they transmit neurovascular bundles between the periosteum and the bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
Slide 15a (464): Fetal Joint
1. Synovial
2. Intervertebral
Summary
synovium (synovial membrane) lines the interior of the joint capsule and secretes lubricating fluid into cavity
articular cartilage is similar to hyaline cartilage but lacks a perichondrium joint cavity
skeletal muscle periosteum
look here to see Sharpey’s fibers and attachment of muscle to the bone (still cartilage this early in development)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Slide 14a (464): Intervertebral Disc, H&E
vertebra (bone of vertebral column)
intervertebral disc with concentric rings of fibrocartilage thin layer of hyaline cartilage vertebra (bone of vertebral column)
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
Slide 23 (NW): Intervertebral Disc
1. Hyaline
annulus fibrosus (Lt. “fiber ring”)
2. Elastic
3. Fibrocartilage
B. Bone
concentric rings of fibrocartilage
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
nucleus pulposus (Lt. “fleshy core”)
c. Appositional growth d. Internal remodeling
gel-like, shockabsorbing tissue at center of disc
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
this large area of discoloration is an artifact of slide preparation
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Common Confusion: Hyaline vs. Elastic Cartilage
Hyaline cartilage: most common form of cartilage; located in the articular surfaces of movable joints, in the walls of larger respiratory passages, in the ventral ends of ribs, and in the epiphyseal plates of long bones
A. Cartilage
1. Hyaline 2. Elastic
Look for: (1) homogenous, slightly basophilic matrix; (2) chondrocytes arranged in small clusters of 2-4 cells
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
Hyaline cartilage
c. Appositional growth
Elastic cartilage: similar to hyaline but with elastic fibers in ECM providing elasticity to the tissue; found in canal of ear, Eustachian tube, epiglottis, and laryngeal cartilages
d. Internal remodeling
3. Types
a. Woven
Look for: (1) presence of elastic fibers in ECM if specialized stains are used; (2) matrix is more heterogeneous and less “glassy” in appearance; (3) greater cell density, thus less ECM between cells; (4) larger chondrocytes than in hyaline
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Elastic cartilage
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Common Confusion: Hyaline vs. Fibrocartilage
Hyaline cartilage: most common form of cartilage; located in the articular surfaces of movable joints, in the walls of larger respiratory passages, in the ventral ends of ribs, and in the epiphyseal plates of long bones
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
Hyaline cartilage
c. Appositional growth
Fibrocartilage: found in intervertebral discs, in attachments of certain ligaments, and in the pubic symphysis; it is essentially a combination of hyaline cartilage and dense CT
d. Internal remodeling
3. Types
a. Woven
Look for: (1) collagen fibers in eosinophilic matrix; (2) usually only individual chondrocytes in lacunae; (3) lacunae arranged in rows or clusters; (4) lack of perichondrium
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Look for: (1) homogenous, slightly basophilic matrix; (2) lack of visible collagen fibers in matrix; (3) lacunae often contain two or more chondrocytes (isogenous group); (4) lacunae immediately rimmed with basophilic matrix (less collagen, more GAGs); (5) generally surrounded by perichondrium (not seen here)
Fibrocartilage
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Common Confusion: Dense Regular CT vs. Fibrocartilage
Dense regular connective tissue: prominent in tendons, ligaments, and surrounding tissues and organs; collagen bundles and fibroblasts aligned in parallel to axis of functional stress
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
Dense regular CT
c. Appositional growth
Fibrocartilage: found in intervertebral discs, in attachments of certain ligaments, and in the pubic symphysis; essentially a combination of hyaline cartilage and dense connective tissue
d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Look for: (1) parallel, closely packed bundles of collagen separated by very little ground substance; (2) fibroblasts are relatively sparse and have elongated nuclei lying parallel to the fibers; (3) cytoplasm of fibroblasts is rarely revealed in H&E stains
Fibrocartilage
Look for: (1) chondrocytes in lacunae; (2) collagen bundles are fewer, less densely-packed, and interspersed among cartilage matrix; (3) tissue generally lacks as uniformly parallel an organization as seen in dense CT; (4) few fibroblasts are seen; (5) chondrocyte nuclei are more oval/round, with perinuclear cytoplasm generally evident, than fibroblast nuclei; (6) chondrocytes usually appear in linear clusters surrounded by cartilage matrix
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Common Confusion: Cartilage vs. Bone
Cartilage: a specialized type of solid connective tissue which, along with bone, is distinguished by its relative rigidity of the extracellular matrix (ECM); hyaline, the most common type, is pictured here
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
Hyaline cartilage
c. Appositional growth
Bone: a specialized type of solid connective tissue which is characterized by a mineralized ECM that stores calcium and phosphate
d. Internal remodeling
3. Types
a. Woven
Look for: (1) vasculature; note the central canal (osteon) containing visible erythrocytes; (2) more ECM and fewer cells; (3) osteocytes are singular and spaced apart; (4) osteocytes are smaller and more condensed than chondrocytes; (5) canals and lamellar organization may be visible
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Look for: (1) lack of vasculature, lymphatics, and nerves; (2) large proportion of cells to ECM; (3) chondrocytes may occur as pairs within a lacuna and tend to be clustered together (isogenous groups) reflecting interstitial growth; (4) chondrocytes are usually larger and rounder than osteocytes; (5) matrix is often not uniform and tends to heterogeneously stain; (6) lack of lamellar architecture
Decalcified bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
Common Confusion: Woven vs. Lamellar Bone
Woven bone: immature, newly-synthesized bone; all new bone, regardless of process of formation, is woven bone; it lacks an organized architecture for the fibers in the ECM
A. Cartilage
1. Hyaline
Look for: (1) lack of lamellar organization of ECM; (2) greater cell density than mature bone with seemingly random arrangement of cells; (3) matrix contains more ground substance so more basophilic staining; (4) deposit of matrix and remodeling is not uniform giving overall mottled appearance
2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation
Woven bone
c. Appositional growth
Lamellar bone: mature bone; remodeled from woven bone by osteoclasts and osteoblast activity; bone matrix is deposited and organized in lamellae (sheets), either in long parallel arrangements on in concentric rings as in osteonal architecture; both cortical/compact bone and trabecular/spongy are lamellar
d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular
Look for: (1) less ground substance in matrix so more eosinophilic staining; (2) lamellar (sheets) arrangement of matrix; (3) in cortical bone, osteons with evident central canals
ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Decalcified lamellar bone
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Summary 1.
Learning Objectives Keywords
a.
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
b.
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
2. 3.
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Cartilage is a specialized type of solid connective tissue that, along with bone, is distinguished from other CT by the relative rigidity of its extracellular matrix (ECM); it generally grows by either appositional or interstitial growth; it consists of two major cell types:
4. 5.
Chondroblasts are generally located at the periphery of cartilage at the interface with the surrounding dense CT (perichondrium); they secrete new cartilage matrix for appositional growth of cartilage, eventually becoming encased within the newlysynthesized matrix. Chondrocytes are chondroblasts that have become encased in cartilage matrix; they are located in spaces in the matrix called lacunae and are responsible for ECM maintenance and occasionally for interstitial growth of cartilage.
The three types of cartilage (hyaline, elastic, fibrocartilage) are distinguished by the characteristics of their matrix (e.g., the dominant type of protein fiber).
Bone, like cartilage, is a specialized type of solid connective tissue; however, it is characterized by a mineralized ECM; newly-formed bone is referred to as woven bone due to its interlaced collagen fibers; woven bone is replaced by lamellar bone (mature) with organized sheets of bone matrix. Lamellar bone is classified as either cortical/compact which is dense and located at the cortex of bones, or cancellous/trabecular which is has an intricate meshwork of bone that fills the medulla of bones, with the interconnected spaces within the meshwork are filled with marrow.
The functional unit of compact bone is the osteon, consisting of a central canal (containing a neurovascular bundle) and concentric rings of bone matrix called lamellae (osteocytes occupy lacunae between adjacent lamellae).
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Summary (cont.) 6. 7.
Bone formation occurs via one of two processes: in intramembranous ossification new bone forms directly from mesenchyme tissue, while in endochondral ossification bone tissue replaces existing cartilage. Bone tissue consists of three major cell types: a.
b. c.
Osteoblasts derive from osteoprogenitor cells from mesenchyme stem cells; they secrete type I collagen and bone matrix proteins (osteoid) as well as calcify the matrix to form new bone. Osteocytes are mature osteoblasts which have become encased by osteoid; they are longlived cells that maintain the bone matrix and are able to communicate via canaliculi between lacunae with other osteoctes to respond to mechanical stressors on the bone. Osteoclasts are multinucleated cells formed from the fusion of hematopoietic progenitor cells; they are responsible for bone resorption.
Labs 6/7 – Cartilage and Bone IUSM – 2016
I.
Introduction
IV.
Slides
II.
III.
Learning Objectives Keywords
A. Cartilage
1. Hyaline 2. Elastic
3. Fibrocartilage
B. Bone
1. General Overview
2. Formation and Growth
a. Intramembranous formation b. Endochondral formation c. Appositional growth d. Internal remodeling
3. Types
a. Woven
b. Lamellar
i. Cancellous/Trabecular ii. Cortical/Compact
C. Joints V.
1. Synovial
2. Intervertebral
Summary
Cartilage and Bone Tissue Compare and Contrast Terms Cartilage vs. Bone Hyaline vs. Fibrocartilage
Chondroblast vs. Chondrocyte Periosteum vs. Endosteum
Appositional vs. Interstitial growth
Cortical vs. Spongy bone Woven vs. Lamellar bone Intramembranous vs. Endochondral oss.
Compare and Contrast (Similarities? Distinctive differences?)
