Studies on the relationship between FSH and germ cells: evidence for selective suppression of FSH by testicular extracts.

The evidence supporting the relationship between the seminiferous epithelium and circulating FSH levels has been reviewed and provides support for the concept that the testis produces a factor capable of specifically controlling FSH concentrations. Detailed quantitative histological studies of the seminiferous epithelium have demonstrated a highly significant inverse relationship between the number of spermatogonia per tubule cross-section and serum FSH levels in men with testicular disorders.