Question

Describe the histology of testis with help of labelled diagram.

Answer 1

Histology of Testis:

1. Externally, the testis is covered by three layers. These are:
   a. Tunica vaginalis: It is the outermost incomplete peritoneal covering made up of connective tissue and epithelium.
   b. Tunica albuginea: It is the middle layer formed by collagenous connective tissue.
   c. Tunica vasculosa/vascularis: It is the innermost layer. It is a thin and membranous layer.
2. Each testis is divided into about 200-300 testicular lobules by fibres from tunica albuginea. Each lobule has 1 to 4 highly coiled seminiferous tubules.
3. Each seminiferous tubule is internally lined by a single layer of cuboidal germinal epithelial cells (spermatogonia) and few large pyramidal cells called Sertoli or sustentacular cells.
4. The germinal epithelial cells undergo gametogenesis to form spermatozoa.
5. Sertoli cells provide nutrition to the developing sperms.
6. Various stages of spermatogenesis can be seen in the seminiferous tubules. The innermost spermatogonial cell (2n), primary spermatocyte (2n), secondary spermatocyte (n), spermatids (n), and sperms (n).
7. Between seminiferous tubules, few groups of interstitial cells (Cells of Leydig) are present.
8. After puberty, interstitial cells produce a type of androgen i.e. testosterone.