Immunocytochemical localization of oestrogen and progesterone receptors in the uterus of the normal bitch during oestrus and metoestrus.

Frozen uterine biopsy samples obtained from eight bitches during oestrus and metoestrus were used to develop immunocytochemical methods for identifying steroid receptors. The use of anti-steroid receptor monoclonal antibodies DAKO ID5 and NCL-PGR resulted in reliable detection of oestrogen and progesterone receptors, respectively. The distribution and heterogeneity of both oestrogen receptor and progesterone receptor expression varied during the oestrous cycle. During oestrus, steroid receptor expression was greatest as indicated by a distinct and homogeneous distribution of nuclear staining within cells of the endometrial glandular and luminal epithelium and myometrium. In contrast, during metoestrus there was an overall reduction in both the number and intensity of staining of nuclei. Distribution and intensity of nuclear staining was heterogeneous. This reduction was obvious within the luminal epithelial cells where nuclear staining was negligible compared with that of the glandular epithelial cells. This method could be used for further receptor studies, particularly in those diseases mediated by steroid hormones such as cystic endometrial hyperplasia and mammary neoplasia.