Chemical messengers between Sertoli cells and neighbouring cells.

The Sertoli cell has been shown to secrete a number of compounds, some of which are postulated to serve as chemical signals to the neighbouring cells. The evidence for such communication between Sertoli cells and Leydig cells is briefly summarized. More emphasis is put on Sertoli cell-germ cell interactions. The morphological observations do not support a direct transfer of material from cell to cell. Therefore, the observed dependency of germ cells on Sertoli cells and vice versa must be explained by diffusion of substances from one cell to the other. Examples of Sertoli cell secretory products whose production is dependent on the type of surrounding germ cells are ABP, plasminogen activator, a somatomedin-like compound, transferrin and a high-molecular weight aromatase inhibitor.