Changes of p27 expression in the epithelium of ectocervix and in endometrium during the menstrual cycle (rows show early and mid follicular phases and mid luteal phase). A) In addition to nuclear staining (white arrow), the cytoplasmic p27 expression is apparent in the upper intermediate layers (white arrowhead) and cytoplasmic and plasma membrane staining in the surface cells (black arrowhead). These two layers are divided by cells showing nuclear p27 only (dotted arrowhead). B) Cells show only nuclear p27 throughout the epithelium. C) Strong surface expression in mature and aging epithelial cells. Note that within cells, the traces of p27 staining are confined to the nuclear envelope (black arrow). D) Strong staining of the stroma and patchy nuclear p27 expression in some (developing) glands (dotted arrow). E) Increased stromal and nuclear staining (vs. D). F) p27 is severely depleted from the nuclei of glandular cells (black arrow) and stroma, but persists in vessels. Dashed line, basement membrane; s, endometrial stroma; v, vessels.