Fig. 4. Structural and vascular defects in Pod1 KO mice. Confocal images are shown of 12.5 dpc gonads double-labeled with antibodies to laminin (green) and CD31/PECAM (red), which labels both germ cells (round) and vascular cells (elongated). In wild-type males at 12.5 dpc (A,C), the green laminin staining delineated numerous testicular cords (tc, arrows). The wild-type testes also displayed the characteristic coelomic vessel, which forms right beneath the coelomic epithelium (C, white arrowheads). In the Pod1 KO testes (B,D), no testicular cords were present and the coelomic vessel was also absent. The coelomic epithelium (blue arrowheads) was highly disorganized and invaginated in many locations. In wild-type females (E,G), no clear morphological organization was observed at this stage of development. However, compared with the control, the Pod1 KO XX gonad (F,H) exhibited a very disorganized surface epithelium, similar to that in gonads from the XY mutant. Of note, germ cell numbers did not appear to be affected in either XY or XX Pod1 KO mice.