Fig. 9. Neural retina development in Otx1^-/-; Otx2^+/- mice. Adjacent paraffin sections of E18.5 wild-type (A,D,G) and Otx1^-/-; Otx2^+/- (B,E,H) retinas were immunostained with antiserum against Ph-H3 (A,B), antibodies against Islet1 (G,H) or stained with Cresyl Violet to determine the amount of apoptosis in the sections (D,E). Note that the number of mitotic (arrows in B compared with A) and apoptotic (arrowheads in E compared with D) cells is greatly increased while those of differentiated cells (compare arrowheads in G and H) is decreased in mutant retinas. Statistical analysis of the number of mitotic, apoptotic and Islet1-positive cells is presented in C,F and I, respectively (n=4). Note that in all cases there is significant difference between control and Otx-deficient mice. enr, ectopic neural retina; gcl, ganglion cell layer; nr, neural retina; pe, retinal pigment epithelium. Bar, 100 µm.