(ABP) by the sertoli cells and helps in the process of spermiogenesis. LH acts on the Leydig cells and stimulates the synthesis of testosterone which in turn stimulates the process of spermatogenesis. Spermatid Spermatogonia Sertoli cells Interstitial cell Fig. .
(a) Cross sectional view of seminiferous tubule Fig. . (b) Seminiferous tubules (Enlarged) XII Std Zoology Chapter XII Std Zoology Chapter Human Reproduction Out of the million eggs women possess during birth, only about to will ovulate before menopause. On the other hand, males produce more than billion sperms in their life time.
The primary follicle gets surrounded by many layers of granulosa cells and a new theca layer to form the secondary follicle . A fluid filled space, the antrum develops in the follicle and gets transformed into a tertiary follicle . The theca layer gets organized into an inner theca interna and an outer theca externa. At this time, the primary oocyte within the tertiary follicle grows in size and completes its first meiotic division and forms the secondary oocyte .
It is an unequal division resulting in the formation of a large haploid secondary oocyte and a first polar body. The first polar body disintegrates. During Fertilization, the secondary oocyte undergoes second meiotic division and produces a large cell, the ovum and a second polar body. The second polar body also degenerates.
The tertiary follicle eventually becomes a mature follicle or Graafian follicle . If Fertilization does not take place, second meiotic division is never completed and the egg disintegrates. At the end of gametogenesis in females, each primary oocyte gives rise to only one haploid ovum.