Process of producing spermatozoa from spermatogonial stem cells by the way of mitosis & meiosis.
Spermatogonia ———- primary spermatocyte ———– secondary spermatocyte ———- spermatid ———- spermatozoa.
In mammals spermatogenesis occurs in the seminiferous tubules of the male testes.
Spermatogenesis continues young (13-14 yr) to old man (60-65 yr age).
Spermatogenesis occurs in different phase.
Division of stem cell to replace themselves.
Spermatogenesis begins with a diploid spermatogonium cell within the seminiferous tubules then divides mitotically & produced two diploid primary spermatocytes.
Each primary spermatocyte then moves into the alduminal compartments of the seminiferous tubule & duplicates its DNA & develops in size.
After develop in size primary spermatocyte undergoes meiosis I to produce two haploid secondary spermatocytes.
Secondary spermatocytes later enter meiosis II & divide to produce haploid spermatids.
Each spermatid begins to grow tail & middle portion developed, thickened where mitochondria gather to form axoneme.
It is the process of production of egg by the female reproductive organ through the meiosis cell division. Process starts in the ovaries of the foetus before birth.
In mammals Oogenesis occurs in the ovaries of female reproductive system.
PROCESS OF OOGENESIS
There are mainly 5 stages in oogenesis.
- Until many oogonia are formed germinal epithelial cells divided repeatedly.
- The oogonia grow to form primary oocytes. It is surrounded by a layer of follicle cell.
- Primary oocyte undergoes the first meiotic cell division and formed secondary oocyte.which is also known as first polar body.
- The follicle cells surrounding the primary follicle develop into the secondary follicle.
The follicle layer of secondary oocyte folds to form the graffian follicle.
After the maturation of graffian follicle it moves towards the surface of the ovary wall and rupture to release the secondary oocyte.
- The secondary oocytes complete meiosis II when it is fertilized by a sperm.
The final products of meiosis II is the ovum and second polar body.
This is the general notes on spermatogenesis and oogenesis.
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