Expression of a secretory product by microvillous and ciliated cells of the human endometrial epithelium in vivo and in vitro

A monoclonal antibody which identifies a component of post-ovulatory endometrial secretions is now shown to be expressed within the cytoplasm and on the cell surface of both microvillous and ciliated epithelial cells. A glandular explantation model was developed in order to study the 'carry over' of this secretion to the regenerative phase endometrium. A loss of cytoplasmic antigen was observed in vitro. However, it was retained on the cell surface in a fashion consistent with its expression at the time of explanation. Mosaicism of expression of this secretory component occurs throughout the secretory-phase and is particularly pronounced at the time of transition from proliferative to secretory phase. It is concluded that both ciliated and microvillous epithelial cells produce a post-ovulatory secretory component which may be retained on the cell surface in the absence of hormonal stimulation.