IMMUNOCYTOCHEMICAL DEMONSTRATION OF PROGESTERONE AND ESTROGEN-RECEPTORS IN FEATHERS AND SKIN OF ADULT HENS

Clinical evidence indicates that ovarian steroids are Involved in the control of moulting in the chicken. This immunocytochemical study inve stigates if feather papillae and growing feathers are target tissues f or ovarian steroids. Progesterone (PR) and estrogen (ER) receptors Her e demonstrated using monoclonal antibodies in feathers and surrounding skin of laying hens. Both receptor types were present in the nuclei o f dermal papillae and in the nuclei of the epidermal germinative layer cells of growing and full-grown feathers. In growing feathers most nu clei of the intermediate layer (ramogenic column, rachis, axial plate) were immunostained, but during the final stages of differentiation in to barbules, only estrogen receptors remained prominent. Skin adjacent to feathers showed ER and PR receptors in nuclei of cells from epider mis, muscles and arteries. During egg-laying pause, plasma progesteron e levels decrease ten-fold and it is supposed that this results in a m uch greater endocrine efficiency of the remaining estrogen levels whic h are only reduced by 50% when egg-laying stops. The moult-inhibiting effect of progesterone in laying hens could be due to its well-establi shed downregulation on estrogen receptors and therefore, on the endocr ine effect of ER at cellular level in feather papillae. Such may accou nt for the presence of both receptor types on the same feather cells, as observed in the present study.