Nourishment of developing sperm remains the responsibility of the sertoli cells. Major functions of sertoli cells are Support, Protection and Nutrition of developing spermatozoa. Different cell lines of the spermatogenic cells and sertoli cells are the structural component of the seminiferous tubules, which is the major stroma and mass of the testis.

The primary sex organ, testis produces male gametes i.e sperms and the androgen i.e. hormone testosterone. The stroma of testis is subdivided into approximately 250 lobules. Each lobule contains several highly coiled tubules, the Seminiferous tubules. The tubules are composed of a complex stratified epithelium surrounded by a thick basal lamina and by alternate layers of collagen and flattened cells called Myeloid cells

The sertoli cells are the major structural components of seminiferous tubules. Proliferation of these cells takes place during the fetal and postnatal period but ceases at or before the onset of Spermatogenesis at puberty and the number is stable in adults.

Light Microscopy of Sertoli Cells

The sertoli cells are some of the largest cells of the body, 70 to 90 mm tall and about 30 mm wide, and extended from basal lamina to the lumen. It possess long and thin mitochondria, and usually have lipofuscin and lipid droplets at the base of their cytoplasm. Sertoli cell nuclei exhibit a variety of shapes, but they are usually oval or pear shaped with significant indentations in the nuclear membrane.

Ultrastructure of Sertoli cells

The outline of sertoli cells is extremely irregular and the germ cells are located in dilations between or in invaginations of the Sertoli cell cytoplasm. Nucleus is located in the basal part of the cell, close to the basal plasmalemma. The nucleolus is prominent. Golgi apparatus is found in the main trunk. Mitochondria are numerous and found in all parts of the Sertoli cell. Most of the endoplasmic reticulum is agranular. Lipid inclusions are common. Microfilaments are abundant in the Sertoli cells.

In the basal cytoplasm numerous membrane bound dense primary and secondary lysosomes are seen. Sertoli cells exhibit two types of Contacts between neighbouring

• Tight junction or occluding junctions or Blood-Testis barrier

• Nexuses or gap junctions.

The occluding inter Sertoli cell junctions are extensive junctional complexes located between adjacent Sertoli cells at a level above the spermatogonia. This barrier segregates the spermatogonia and early preleptotene primary spermatocytes within the basal compartment and prevents the entry of blood borne substances, such as IgG, from diffusing between cells into the adluminal compartment These junctions subdividing the interior of the tubules into two compartments:

● Basal Compartment

● Adluminal Compartment.

This barrier segregates the spermatogonia and early preleptotene from primary spermatocytes within the basal compartment and prevents the entry of blood borne substances, such as IgG, from diffusing between cells into the adluminal compartment. The gap junctions are different types of contacts found between Sertoli cells and germ cells. These are desmosomelike devices found between Sertoli cells and all types of germ cells.

Sertoli cells have receptor sites for FSH.