Effect of Progesterone on Proteins Vectorially Secreted by Glandular Epithelial Cells of Guinea Pig Endometrium: Modulation by Homologous Stroma

The endometrium is permissive to blastocyst implantation only during a brief receptive interval following appropriate hormonal stimulation (Martel et al. 1981; Psychoyos 1986; Beier et al. 1991). Changes in uterine epithelial cell properties during the preimplantation period are required to prepare the endometrium for implantation. A number of changes in uterine apical membrane properties (Anderson et al. 1986; Classen-Linke and Denker 1990; Seif and Aplin 1990) and secretory products of the uterine epithelium have been described in various species (Bell 1990). Some of these changes appear correlated with the acquisition of the receptive state, although none has been conclusively demonstrated to play a direct role in blastocyst attachment or invasion.