1. 11.4 Reproduction

2. Gametogenisis

3. I. Spermatogenesis- the production of male gametes.
A. Structure:
1. The testes are located outside of the body in the scrotum to provide a cooler temperature for sperm production.

4. 2. The site of spermatogenesis in the testis are the many tiny convoluted seminiferous tubules (about 250 meters)

5. 3. Each seminiferous tubule is bounded by a basement membrane and layer of smooth muscle that are responsible for the peristaltic movements of the tubule.
4. In the center of the tubule is a fluid filled lumen containing immature sperm called SPERMATAZOA.

7. 5. The walls of the tubule are made up of sperm cells at different stages of development and specialized nurse cells called SERTOLI CELLS that provide nutrition for the developing SPERMATAZOA.

8. 6. LEYDIG CELLS (Interstitial Cells) are found in between the tubules and is responsible for TESTOSTERONE production.

10. B. Process of Spermatogenesis:
1. Near the outer wall of the seminiferous tubules are diploid (2n) germinal epithelium cells called SPERMATAGONIUM (s) that are undergoing MITOSIS
Mitosis- Sperm production begins at puberty and continues through out life. Mitosis makes an endless supply of diploid (46 chromosomes) cells for sperm production.

11. 2. MITOSIS produces many copies of SPEMATAGONIA (pl).
Some increase significantly in size and are now called PRIMARY SPERMATOCYTES that will enter MEIOSIS.
Meiosis- is a “reduction division”
process that reduces the number
of chromosomes in half by doing
two sets of divisions (Meiosis I and Meiosis II) producing
4 gametes.
Meiosis Animation

13. 3. These cells will undergo Meiosis I which will result in two daughter cells with half the number of chromosomes (haploid= 23) called SECONDARY SPERMATOCYTES.

15. 4. The two SECONDARY SPERMATOCYTES enter into MEIOSIS II forming 4 SPERMATIDS with half of the number of chromosomes.

17. Pair up the appropriate label and annotation:

19. 5. Once MEIOSIS is completed the SPERMATIDS must differentiate into a fully functioning SPERMATAZOA.
a. Head- contains the nucleus and the ACROSOME- organelle that contains hydrolytic or digestive enzymes to penetrate the egg.
b. Midpiece- with helical mitochondria for ATP production.
c. Flagella- whip- like tail made up of microtubules used for motility.

20. Label:

22. 6. The developing sperm cells need nutrients during this period of differentiation and attaches to the specialized nurse cells called SERTOLI CELLS.

23. 7. Each of the stages of meiosis have moved the resulting cells closer to the fluid filled lumen of the seminiferous tubule.
8. The SPERMATIDS are swept up into the EPIDIDYMIS where they will be stored.

25. C. Hormonal Control of Spermatogenesis
1. LH (secreted by pituitary)– stimulates LEYDIG cells to produce testosterone.
2. FSH (secreted by pituitary)– stimulate the meiotic division of primary spermatocytes into
secondary spermatocytes.
3.Testosterone-Development of secondary spermatocytes into mature sperm.

26. SUMMARY:

29. Semen production

30. (About 400 MILLION sperm produced each day.)
Maturing sperm are passed onto a long coiled tube, the EPIDIDYMIS (upper rear part of each testis) where they further mature, become motile, and are stored until ejaculation. ( about 20 days)
(About 400 MILLION sperm produced each day.)

31. b. PROSTATE GLAND - alkaline-neutralizes acidic environment of female.
Exocrine glands produce secretions for the transport of sperm called SEMEN.
a. SEMINAL VESSICLE- provides a sugar (fructose) rich fluid used to nourish the sperm and provide energy and mucus for protection.
b. PROSTATE GLAND - alkaline-neutralizes acidic environment of female.