HUMAN REPRODUCTION 

HUMAN REPRODUCTION


Sectional view of male penis

The male reproductive system is located in pelvic region which is under abdominal cavity. It includes testes  along with accessory ducts, accessory glands and external genitalia. The primary sex organ in males is testes. It is located outside abdominal cavity within a pouch called scrotum. The scrotum hepls in maintaing the low temperature of testes (2-2.5°c lower than body temperature) necessary for sperm formation. In adults, testes is oval in shape with length 4-5 cm and width 2-3 cm. The testes is covered by a layer of dense muscles. The first layer is called cremaster-a skeletal muscle layer which helps in positioning of scrotum. The second layer of testes is called Dartos- a smooth muscle layer. All the blood vessels comes to testes through a opening in abdominal cavity called inguinal canal. Each testes has about 250 compartments called testicular lobules. 



Part of testis is  open to show inner details

Each lobule contains highly coiled seminiferous tubules in which spermatogenesis occurs.
Each seminiferous tubules  consists of two cells called male germ cell(Spermatogonium),where by meiotic division sperms are formed.It also consists of sertoli cells or nurse cells, which provide nutrients for developing sperms.The region outside seminiferous tubules consists of  interstitial cells or leydig cells which mainly secretes hormones in males called Androgen.eg-Testosterone.All this is linked with a system in our body called nuroendocrine mechanism.Firstly,Hypothamus secretes GnRH(Gonadotropin Releasing Hormone) which acts on Anterior Pituitary.Then Pituitary secretes other hormones called FSH(Follicular Stimulating Hormone) and LH(Luteinising Hormone ) also called ICSH(Interstitial Cell Stimulating Hormone) in males.The ICSH acts on leydig cells to secrete Androgen.The FSH acts on sertoli cells to release Androgen Binding Protein.It mainly holds the sperm  in lumen of seminiferous tubules.


                         

                           Transverse section of Seminiferous Tubules

NOTE : Negative Feedback Mechanism : When something stops its own production by going back to its parents. For Example : If Testosterone production is more in body then it causes harm to our body.So,it produes negative feedback mechanism, which means it goes back to pituitary and stop production of LH and FSH.Then LH and FSH goes back to Hypothalamus and stops it.


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