Inhibin in the Hen

The role of the gonadal hormone inhibin has not been extensively examined in the hen. A bovine radioimmunoassay kit has been used to assess plasma levels of immunoreactive inhibin throughout the ovulatory cycle, in response to follicle removal, and after stimulation of follicle growth. Homologous chicken radioimmunoassays for luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were used to assay plasma gonadotropins. No significant peak of immunoreactive inhibin was detected throughout the ovulatory cycle in spite of a preovulatory surge of LH. Removal of preovulatory follicles caused a decrease of plasma immunoreactive inhibin whereas stimulation of follicle growth with equine chorionic gonadotropin increased plasma immunoreactive inhibin levels. Associated with the fall in inhibin level upon follicle removal is an acute rise in FSH with no concomitant change in LH.