Figure 3. Endocrine regulation of spermatogenesis.
PI - pituitary gland, hypothalamus, SC - Sertoli cells, LU - lumen of seminiferous
tubule, LC -Leydig cells, AR - arteriole, MC - myoid cells, SP - spermatogonia, T
- testosterone, FSH - follicle stimulating hormone, LH - luteinizing hormone, In
- inhibin, Act - actvin, EGF - epidermal growth factor, FasL and Fas - ligand and
receptor system involved in apoptosis of germ cells
- decrease (negative feed back)
+ increase (positive feed back)
Sertoli cells (SC) under the influence of FSH regulate spermatogenesis by activin
(Act), androgen binding protein and direct interactions with spermatogonia and spermatids.
Leydig cells regulate spermatogenesis by achieving high intratesticular testosterone
concentration. Epidermal growth factor (EGF) is produced by LC and controls mitotic
divisions of germinal epithelium. EGF also stimulates divisions of peritubular myoid
cells which in return produce another paracrine hormone peritubular myoid substance
(PmodS).