Figure 2

Cellular localisation of PR isoforms. (Panel a) High power images of PR immunostaining with clone 1A6 indicating immunoreactivity in the cytoplasm of the amnion epithelial cell and the chorionic cytotrophoblast. Note the absence of staining in the blue nucleus of either cell type. The plasma membrane of the cell is shown by the arrows, the apical surface by the white asterix and a void between the nucleus and the cytoplasm by the red V. (Panel b) A low power image of PR immunostaining of the term placenta with clone 1A6 antibodies indicating immunoreactivity in the syncytiotrophoblast layer (arrow), but absent elsewhere. (Panel c) High power images of PR immunostaining of term placenta indicating the presence of cytoplasmic PR in the syncytiotrophoblast but not nuclear PR-B and PR-A isoforms (panel c; 1, 2, and 3); whereas basal plate decidual cells contained both cytoplasmic and nuclear PR isoforms (4, 5, and 6 arrowed). These data suggest the cytoplasmic PR staining in amnion epithelial cells, cytotrophoblasts, syncytiotrophoblasts and decidual cells, is not PR-B or PR-A, but PR-S, PR-M or PR-C. Bar = 50 μm, except panel A where Bar = 5 μm. Data are representative of six independent samples.