Male Reproductive System Laboratory Exercise 59 Background The organs of the male reproductive system are specialized to produce and maintain the male sex cells, to transport these cells together with supporting fluids to the female reproductive tract, and to produce and secrete male sex hormones. These organs include the testes, in which sperm cells and male sex hormones are produced, and sets of internal and external accessory organs. The internal organs include various tubes and glands, whereas the external structures are the scrotum and the penis.

Materials Needed Textbook Human torso model Anatomical chart of the male reproductive system Compound light microscope Prepared microscope slide of the following: • Testis section • Epididymis (cross section) • Penis (cross section)

Purpose of the Exercise Review the structure and functions of the male reproductive organs and examine some of these organs microscopically.

Procedure A – Male Reproductive Organs 1. Label figures 59.1 and 59.2. 2. Observe the human torso model and the anatomical chart of the male reproductive system. Locate the following features: testes, inguinal canal, spermatic cord, epididymis, vas deferens, ejaculatory duct, seminal vesicles, prostrate gland, bulbourethral glands, scrotum, penis 3. Complete Part A of the laboratory report.

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Procedure B – Microscopic Anatomy 1. Obtain a prepared microscope slide of a human testis section and examine it, using low-power magnification. Locate the thick fibrous capsule (tunica albuginea) on the surface and the numerous sections of seminiferous tubules inside. 2. Focus on some of the seminiferous tubules, using high-power magnification. Locate the epithelium, which forms the inner lining of each tube. Within this epithelium, identify some sustentacular cells or supporting cells (Sertoli’s cells), which have pale, oval-shaped nuclei, and some spermatogenic cells, which have smaller, round nuclei. Near the lumen of the tube, find some darkly stained elongated heads of developing sperm cells. In the spaces between adjacent seminiferous tubules, locate some isolated interstitial cells (cells of Leydig). 3. Prepare a labeled sketch of a representative section of the testis in Part B of the laboratory report. 4. Obtain a microscope slide of a cross section of epididymis. Examine its wall, using high-power magnification. Note the elongated, pseudostratified columnar epithelial cells that comprise most of the inner lining. These cells have nonmotile stereocilia (microvilli) on their free surfaces. Also note the thin layer of smooth muscle and connective tissue surrounding the tube. 5. Prepare a labeled sketch of the epididymis wall in Part B of the laboratory report. 6. Obtain a microscope slide of a penis cross section, and examine it with lowpower magnification. Identify the following features: corpora cavernosa, corpus spongiosum, tunica albuginea, urethra, skin. 7. Prepare a labeled sketch of a penis cross section in Part B of the laboratory report. 8. Complete Part C of the laboratory report.

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Figure 59.1 Label the major structures of the male reproductive system in this sagittal view.

Figure 59.2 Label the diagram of (a) the sagittal section of a testis and (b) a cross section of a seminiferous tubule.

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Part A Complete the following statements: 1. Each testis is suspended by a (an) ____________________ within the scrotum. 2. The descent of the testes from near the developing kidneys is stimulated by the male sex hormone ____________________. 3. The descent of the testes is aided by a fibromuscular cord called the ____________________. 4. As the testes descend, they pass through the ____________________ of the abdominal wall into the scrotum. 5. Connective tissue subdivides a testis into many ____________________, which contain seminiferous tubules. 6. The ____________________ is a highly coiled tube on the surface of the testis. 7. The ____________________ cells of the epithelium that line the seminiferous tubule give rise to sperm cells. 8. ____________________ is the process by which sperm cells are formed 9. Immature sperm cells formed from secondary spermatocytes during meiosis are called ____________________. 10. The number of chromosomes normally present in a human sperm cell is ____________________. 11. The anterior end of a sperm head, called the ____________________, contains enzymes that aid the penetration of an egg cell at the time of fertilization. 12. Sperm cells undergo maturation while they are stored in the ____________________. 13. The secretion of the seminal vesicles is rich in the monosaccharide called ____________________. 14. Prostate gland secretion helps neutralize seminal fluid because the prostate secretion is ____________________.

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15. The secretion of the ____________________ glands lubricates the end of the penis in preparation for sexual intercourse. 16. The pH of seminal fluid is slightly _____________________. 17. The dartos muscle is in the subcutaneous tissue in the wall of the ____________________. 18. The sensitive, cone-shaped end of the penis is called the ____________________. 19. ____________________ is the movement of sperm cells and various glandular secretions into the urethra. 20. ____________________ is the process by which semen is forced out through the urethra.

Part B 1. Prepare a labeled sketch of a representative section of the testis.

2. Prepare a labeled sketch of a region of the epididymis.

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3. Prepare a labeled sketch of a penis cross section.

Part C Briefly describe the function of each of the following: 1. sustentacular cell (supporting cell)

2. spermatogenic cell

3. interstitial cell

4. epididymis

5. corpora cavernosa and corpus spongiosum

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