Describe the histology of human testis. Write a note on human sperm.

Histology of testes:

The testis is surrounded by three protective layers which are known as tunicae. These three layers are Tunica vaginalis, Tunica albuginea, and Tunica vasculosa. Each testis contains about 250 compartments called testicular lobule and each lobule contains one to three highly coiled seminiferous tubules where sperms are produced. The stratified epithelium of seminiferous tubules is made up of two type of cells- Sertoli cells and Spermatogenic cells or male germ cells.

Sertoli cells are elongated and pyramidal which partially envelope the spermatogenic cells and nourish the spermatozoa. Spermatogenic cells are stacked in 4-8 layers that occupy the space between the basal lamina and the lumen of the tubule. These cells divide several times and differentiate to form spermatozoa.

Between the seminiferous tubules are present the Leydig cells. These cells secrete testosterone hormone that controls spermatogenesis.

Short note on Human Sperm:

A mature human sperm cell is a microscopic and tadpole-shaped cell. It consists of an oval head, a cylindrical body having neck and body piece and an elongated tail.

Head contains the nucleus which has a haploid number of chromosomes i.e. 23 in human and an acrosome which contains hydrolytic enzymes called sperm lysin e.g. hyaluronidase. The acrosome is involved in the penetration of the layers of sperm cells surrounding the egg immediately before fertilization.

The short neck consists of a pair of centrioles at a right angle to each other. The middle piece is enlarged by the presence of many mitochondria. Mitochondria carry out aerobic respiration and produce ATP which helps in the movement of sperm.

The tail is several times longer than the head and contains cytoplasm. It has two parts- main piece and end piece. The main piece has a covering of cytoplasm and the end piece consists of a naked filament but lacks cytoplasm.