ABSTRACT
Among the earliest observations of cytoskeletal phenomena in uterine epithelial cells were those of Pollard and Finn (1972) who reported a “lighter staining” in the terminal web area around the time of attachment. More recent focus on the cytoskeleton of these cells has been fuelled by different interests including the utility of intermediate filament proteins as indicators of clinical conditions. Dabbs et al. (1986) identified keratin and vimentin during the proliferative phase of the menstrual cycle and reported that vimentin was localized to perinuclear regions. In contrast, Khong et al. (1986) could only localize cytokeratin in human glandular epithelial cells and found no staining for vimentin. Viale et al. (1988) similarly followed these two cytoskeletal proteins in epithelial tumors of glandular epithelial cells and reported that vimentin was useful as a marker of tumour differentiation. Hochfeld et al. (1990) used immunofluorescence to show that while cytokeratin was seen in an unchanging distribution in rabbit uterine epithelial cells during early pregnancy, vimentin distribution which was basolateral early in pregnancy was also found apically as implantation proceeded. Similarly, Classen-Linke and Denker (1990) studied intermediate filament related proteins associated with desmosomes (desmoplakin I and II) with immunocytochemistry and reported a shift from subapical to basolateral arrangement as early pregnancy progressed. In women using Norplant, a long-term levonorgestrolreleasing contraceptive implant, Wonodirekso et al. (1993) using immunofluorescence, found a reduction in cytokeratins 8, 18 and 19 in uterine luminal epithelial cells and also stated that there was a shift in distribution from apical in controls to apical and basal in Norplant-treated patients. This reduction in cytokeratins and the
altered distribution was thought to contribute to the atrophic endometrium seen in these patients. In a similar vein, Guillomot (1999) has recently reported that cytokeratins 8, 18, and 19 are lost from goat uterine epithelial cells in contact with the trophoblast and has suggested that the loss might contribute to the flattening of the epithelium which accompanies implantation in ruminants.
