Expression of an oestrogen receptor-related antigen in human endometrium: a microphotometric study

The expression of an oestrogen receptor-related antigen has been measured by microspectrophotometry in the glandular epithelium and stroma of tissue sections from endometrial biopsies of women administered exogenous replacement of sex steroids because of premature ovarian failure. We have demonstrated that previously dormant endometrium is capable of expressing an antigen related to oestrogen receptors and that its distribution is influenced by the sex steroid environment. Immunohistochemical staining was more intense (P less than 0.001) in the glandular compared to the stromal cells in tissue exposed solely to oestradiol. With the administration of progesterone, the stromal staining intensity increased (P less than 0.0001) and that of the glandular staining decreased (P less than 0.0001). No assumption, however, has been made to infer that colour is stoichiometrically related to the concentration of antigen present. Further validation of immunohistochemical procedures is required because histological localization and measurement of immunohistochemical staining may be straightforward, but its relationship to antigen concentration remains unproven.