An immunohistochemical study of steroid binding by endometrial glandular epithelial cells throughout the menstrual...

An immunohistochemical technique was used to demonstrate oestrogen and progesterone binding by endometrial glandular epithelial cells at various stages of the menstrual cycle. A cross-section of steroid binding sites, including low affinity, concentration dependent Type II and III binding sites, were demonstrated but only in cells which contain the classical high affinity receptor. The technique demonstrated both free binding sites and receptor-hormone complexes within the cytoplasm but was poorly effective in demonstrating nuclear complexes. Oestrogen binding sites were shown to reach a peak during the late proliferative and early secretory phases of the cycle: oestrogen binding capacity remained high during the mid and late secretory phases. Progesterone binding capacity rose progressively throughout the proliferative and early secretory phase.