Name: Male Reproductive Anatomy
Uploaded: 2019-07-19
Duration: 17 min 6 s
Description: Watch this video to learn about the anatomy of the male reproductive system and the components of the ejaculatory pathway and glands that generate semen.

Question

Describe briefly with labelled diagram of structure of testis. Mention the functions of hormones secreted by testes.

Accepted Answer

Each testis is approximately 4-5 cm in length, 2.5 cm in width and 3 cm in thick (anterioposterior). Each adult testis weighs about 10-20 gms. The testis is externally enclosed by two coverings: tunica vaginalis and tunica albuginea. Tunica vagina is a peritoneal layer of flat cells with a narrow coelomic cavity present on one side of each testis. Tunica albuginea is the actual covering of the testis, and this tough capsule is made up of white fibrous connective tissue. The inner surface of the tunica albuginea protrudes several incomplete fibrous septa or trabeculae which radiate into the mass of the testis and incompletely divide it a number of pyramidal-shaped testicular lobules or lobule testis (about 250 compartments). Each lobule contains one to three extremely convoluted sperm externally linked by a fibrous connective tissue layer, called a basement membrane. Inside the basement membrane, some large elongated supporting cells, called Sertoli cells or nurse cells remain attached, and they formed the blood-testis barrier by making tight junctions between adjacent Sertoli cells near the basement membrane.

Functions of hormones secreted by testes:
Testosterone, Inhibin, Activin, Estrogen are the hormones secreted by testes:
Functions of testosterone:
Testosterone shows its effect on Gametogenesis, fetal development, secondary sex organs, secondary sex characters, muscular growth, bone growth, metabolism, RBC production, electrolytes and water balance, sperm, sexual behaviour.

Functions of inhibin:
Inhibin is a protein hormone secreted by the Sertoli cells of tests. Inhibin regulates the secretion of FSH from the anterior pituitary. It controls spermatogenesis by regulating FSH secretion.

The function of Activin:
Like inhibin, activin is also a peptide hormone secreted by the Leydig cells, and it has homology to the Tumor growth factor-B or TGF-B gene family. Activin is made up of BABB or BABA or BBBB peptide subunits and unlike inhibin, stimulates FSH secretion by the positive feedback effect. Thus, activin also controls spermatogenesis by regulating pituitary FSH secretion.

The function of Estrogen:
A minute amount of estrogen is also formed by the Sertoli cells of the testes. Estrogen plays an important role in spermatogenesis, especially in the spermiogenesis phase.

Describe briefly with labelled diagram of structure of testis. Mention the functions of hormones secreted by testes.

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