Immunohistological localization of human endometrial secretory protein, 'pregnancy-associated endometrial α2-globulin' (α2-PEG), during the menstrual cycle

Abstract

The distribution of α2-PEG, a human analogue of β-lactoglobulin, in endometrium at different phases of the cylcle was determined using immunohistochemistry with monoclonal and polyclonal antibodies. In the epithelial cells of glands in the functional zone of the endometrium, α2-PEG was first detectable from Days 19 to 21 during the mid-luteal phase and maximal immunostaining was observed during the end of the late luteal phase. Intense staining in the glandular secretions and weaker staining in surface luminal epithelial cells during this period were observed. A minor population of basal glands contained α2-PEG during the follicular phase. These results suggest that α2-PEG synthesis by the glandular epithelium of the regenerated endometrium is hormonally regulated. Maximal staining occurring during the late luteal phase suggests that regulation may be related to the hormonal requirement for pre-decidualization rather than that required for histologically defined glandular epithelial secretion.