1. Male Reproductive System
Chapter 17
Male Reproductive System

2. FIGURE 17.1 part 1
The male reproductive system

3. FIGURE 17.1 part 2
The male reproductive system

4. Each testis contains about 250 meters of seminiferous tubule
FIGURE 17.2
The internal structure of the testis and epididymis
Each testis contains about 250 meters of seminiferous tubule

5. Two Major Functions of Testes
Testes: produce sperm (spermatogenesis)
Production Site: seminiferous tubules
About 250 meters of tubule/testis
100 – 300 million sperm/day produced
Testes also produce male hormones (testosterone)

6. Delivery of Sperm to the Egg
The duct system stores and transports sperm
Delivery through reproductive tubules: epididymis  vas deferens  urethra  penis

7. Delivery of Sperm to the Egg
The seminal vesicles and prostate gland (accessory glands) produce most of the volume of semen
The penis transfers
sperm to the female

8. The organ where sperm are produced is
Testes
Prostate gland
Seminal vesicle
Penis

9. Sperm Production
Sperm development involves reduction in the number of chromosomes and in the structure of sperm cells
Several cell divisions of mitosis and meiosis
Purpose: produce a large number (> 100 million/day) of sperm with half the number of chromosomes of somatic cells (haploid)

10. Figure: 19-11
Title:
Comparison of spermatogenesis and oogenesis.
Caption:
Meiosis results in haploid cells that differentiate into mature gametes. Spermatogenesis produces four sperm cells that are specialized to transport the male’s genetic information to the egg. Oogenesis produces three polar bodies and one ovum that is packed with nutrients to nourish the early embryo.

11. FIGURE 17.3
The stages of spermatogenesis in the wall of a seminiferous tubule. As the cells that will become sperm develop, they are pushed from the outer wall of the tubule to the lumen, or central canal.

13. (Leydig cells)

15. FIGURE 17.4
The structure of a mature sperm (spermatozoan)

16. The organ where sperm are produced is
Prostate gland
Testes
Seminal vesicle
Ovary

17. Mature sperm contain: 46 chromosomes
The same number of chromosomes as the father
23 chromosomes
Half the number of chromosomes as the father

18. Male Reproductive Hormones
Testosterone
Source: Interstitial (Leydig) cells in testes
LH: stimulates production of testosterone in interstitial (Leydig) cells
FSH: enhances sperm formation by Sertoli cells

19. Testosterone secretion is regulated by a negative feedback loop (see in class worksheet)

20. The Male Reproductive System
The hypothalamus (neurosecretory cells) releases gonadotropin-releasing hormone (GnRH)
GnRH stimulates the anterior pituitary gland to secrete luteinizing hormone (LH)
LH stimulates the production of testosterone by the testes

21. The rising testosterone level inhibits the release of GnRH to complete the loop

23. Actions of Testosterone on Target Tissues
Controls growth and function of male reproductive tissues (e.g., prostate & seminal vesicles)
Secondary sexual characteristics: muscle, auxiliary hair, larynx, balding pattern
Stimulates aggression and sexual behavior

25. Testosterone has effects on:
Male secondary sexual characteristics, e.g., muscle, beard growth
Prostate gland
Sex drive

26. TABLE 17.2
REVIEW OF HORMONES IMPORTANT IN THE REGULATION OF MALE REPRODUCTIVE PROCESSES

27. TABLE 17.1
REVIEW OF MALE REPRODUCTIVE SYSTEM

28. The function of the prostate gland is to:
Produce sperm
Produce testosterone
Produce secretions (semen) that make sperm mobile
Store sperm