Brent Cornell

    
The process of gametogenesis occurs in the reproductive organs (gonads) of the male and female

• In males, the gametes are produced within the seminiferous tubules of the testes
• In females, the gametes are produced by the ovaries

Seminiferous Tubule

• The testes are composed of seminiferous tubules which produce sperm
• Each tubule is surrounded by a basement membrane which is lined by germline epithelium
• The germline epithelium will divide by mitosis to make spermatogonia (which divide by meiosis to make spermatids)
• The spermatids differentiate into functional spermatozoa, which are then released into the lumen of the tubule
• These developing spermatozoa are nourished by Sertoli cells, which reside in the tubule lining
• Outside of the tubules are blood capillaries and interstitial cells (Leydig cells) which produce testosterone

Ovary

• The ovary contains follicles in various stages of development
• These follicles will develop over the course of a menstrual cycle and hence will not always be apparent upon inspection
• Primordial follicles contain egg cells that have been arrested in prophase I (primary oocytes)
• Some of these follicles will develop each month into primary follicles and then secondary follicles
• Each cycle, one follicle will become a dominant Graafian follicle and rupture to release the secondary oocyte
• The ruptured follicle will then develop into a short-lived corpus luteum, which secretes key ovarian hormones
• Eventually the corpus luteum will degenerate to form a corpus albicans
  
  

Cross-Sections of Reproductive Tissue

Spermatogenesis in the seminiferous tubules starts at the outer lining of the tubule (germline epithelium)

• As the germ cells divide by meiosis they move towards the inner lining before being released into the lumen as sperm
• Non-dividing cells within the tubule lining will represent the Sertoli cells, which nourish and support the spermatocytes
• Cells located externally to the tubule will likely represent interstitial cells (Leydig cells), which produce testosterone

Oogenesis in the ovaries is not a continuous process and proceeds according to a monthly menstrual cycle

• Consequently, certain developing follicles will only be visible at particular stages in the cycle
• As a follicle matures it will grow larger in size, allowing for comparisons to be made between primary and secondary follicles
• Unlike in spermatogenesis, the outer germline epithelium of the ovaries does not directly contribute to gamete formation

Male and Female Reproductive Tissue

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