Histological analysis of the overlapping effect of hypophyseal hormones on the cockerel's testes.

Histological examination of cockerel testes revealed the overlapping effects of FSH and TSH. Within the dose-range studied (20-160 microgram FSH and 27.5-220 microgram TSH), both hormones increased the cell number in the seminiferous cords including the number of spermatogonia, primary spermatocytes and pre-Sertoli cells. They also enhanced the mitotic activity of spermatogonia and accelerated spermatogenesis. Peak effects were observed after treatment with 160 microgram FSH and 55 microgram TSH dose. Liquefaction of cords due to hormone treatment was indicative of an acceleration of testicular ontogeny. Cross-effects of the two hormones were explained by receptor immaturity i.e. in the early stage of ontogenesis the receptors can bind both hormones due to the similarities in their structure. The maximum effects of the hormones were different, that of FSH being more marked.