1. Human Reproduction
Spermatogenesis

2. Spermatogenesis
Sperm production begins during puberty and is stimulated by the release of hormones
Sperm production is controlled by the hypothalamus and ant. Pituitary through negative feedback

3. Spermatogenesis
Hypothalamus releases gonadotropin releasing hormone (GnRH) which triggers ant. pit. To release FSH and LH
FSH triggers seminiferous tubules to produce sperm
LH triggers testosterone production by Leydig cells (interstitial cells) which increases sperm production

4. Testosterone Produced by interstitial cells in the Testes
Also responsible for Secondary sex chars.
Voice Deepens
Body Hair
Strengthening of muscles
Sex drive

5. Hormonal control

6. Spermatogenesis: The making of sperm
Seminiferous tubules in the testes are the site of sperm cell production
Lumen of tubules is lined with spermatogonia
46 chromosomes
Undergo mitosis to form primary spermatocytes
primary spermatocytes undergo meiosis to produce secondary spermatocytes (46 Chromosomes *) and eventually spermatids (23 chromosomes)
One primary spermatocyte will eventually produce four sperm cells

8. Spermatogenesis Spermatogenesis occurs at the onset of puberty
Several hundred million produced/day
Formation of a mature sperm cell takes about 70 – 80 days
Sperm cells mature in the epididymis
Develop flagella and begin to swim within 4 days

9. Spermatogenesis

10. Mature Sperm

11. Human Reproduction
Oogenesis

12. Oogenesis
All follicles are produced in the ovaries during the first during the 1st six months of fetal development
Max. of 7 million produced
2 million left at birth
400,000 at onset on puberty
Approx mature ova develop and are released during the reproductive years

13. Oogenesis Follicles consist of two types of cells:
Primary oocyte
Granulosa cells
Clusters of these cells are called primordial follicles
Granulosa provide nutrients, chemical signals, and protection for the developing follicle

14. Oogenesis 6-20 primary follicles begin to mature each month
Only one follicle fully matures and is released from one ovary each month during reproductive years

15. Ovulation
The ovum is released out of the ovary and will move into the fallopian tube
Remaining follicular cells change and become the corpus luteum
Secretes progesterone and estrogen
If ovum remains unfertilized, corpus luteum degenerates and new cycle will begin

17. Hormonal control Cyclic process in females (continuous in males)
Hypothalamus secretes GnRH
Stimulates LH and FSH in ant. Pit.
Effects of LH and FSH on ovaries varies during the cycle

20. The Ovarian Cycle 28 days long, divided into 3 phases
Follicular phase (12 days)
Luteal phase (11 days)
Menstrual phase (approx. 5 days)