Chicken gonadotrophins: their effects on the testes of immature and hypophysectomized japanese quail.

Five-week old Japanese quail held under short daylengths (8L/16D) were injected daily for two weeks with 20 mug/day of purified chicken luteinizing hormone (LH) or with one of two chicken follicle-stimulating hormone (FSH) fractions. Both intact and hypophysectomized birds were used. After killing, the testes were weighed and fixed for light- and electron-microscopy. Following hypophysectomy testicular weights fell significantly below those of saline-injected controls, indicating that short day conditions are not equivalent to "physiological hypophysectomy", the pituitary-gonadal axis continuing to function at a low level. Chicken LH stimulated differentiation of the interstitium, producing mature Leydig cells containing the full complement of organelles typical of steroid-secretion. In addition it induced some testicular growth caused by spermatogonial division and partial differentiation of the Sertoli cells. This effect was assumed to be a secondary response to androgen secretion but a direct action of chicken LH on the tubules is not dismissed. LH given to intact quail caused greater testicular growth, presumably due to synergism with endogenous hormones. Both chicken FSH fractions induced testicular growth and development; in intact birds the effects were similar to those observed in intact LH-treated birds. In hypohysectomized quail given FSH the testicular weights were greater than in hypophysectomized LH-treated birds and the seminiferous tubules were larger. Sertoli cells were stimulated and pachytene spermatocytes were numerous. Leydig cell differentiation was minimal in all FSH-treated birds, being less pronounced in hypophysectomized than in intact birds.