Immunohistochemical localization of PR and PRB in the superficial endometrial stroma (Str), glands (G) and luminal epithelium (Le). Positive nuclear immunostaining for PR is present in the study groups as shown: OVX (a); CEE (c); MPA (e); CEE /MPA (g), and TAM (i). Nuclear PRB immunostaining is shown for: OVX (b); CEE (d); MPA (f); CEE /MPA (h) and TAM (j) groups, (bar = 30 μm). A negative control is shown for PR where the first antibody is replaced by mouse IgG (k). Positive controls for PRB immunostaining in human endometrium (l) and breast tissue from a CEE treated monkey (m), (bar = 30 μm).