Seasonal and photoperiod-induced changes in the secretion of alpha-melanocyte-stimulating hormone in Soay sheep: temporal relationships with changes in beta-endorphin, prolactin, follicle-stimulating hormone, activity of the gonads and growth of wool and horns

aparato genital blood castration corne cuernos dimension dimensions fsh genital system gonads hfs horns light regimes ovin ovinos prolactin prolactina prolactine regimenes de luz saison sang sangre seasons secretion sex sex differences sexe sexo sheep size testes testicule