Fig. 3. Uterocervical junction forms in the Wnt5a mutant despite the lack of an identifiable cervix at birth. (A) Haematoxylin-Eosin staining of a Wnt5a mutant posterior graft at low magnification. Scale bar: 400 µm. (B,C) High magnification of boxed areas in A showing the transition from simple columnar epithelium to stratified epithelium (arrowhead; scale bar: 40 µm). The transition is accompanied by a correct formation of thick smooth muscle layers in the uterine area and sparse smooth muscle bundles in the vaginal region as shown by smooth muscle myosin heavy chain in situ hybridization (D, SMHC). (E) Wnt7a also shows a normal and sharp boundary of expression at the level of the uterocervical transition and Wnt4 (F) expression shows the correct pattern of epithelial (ep) and stromal (st) expression in the uterus (proestrus stage) and stratified epithelium (se) in the vagina (see insets).