Fig. 5. Decreased BMP activity in the Emx2 mutant forebrain. (A-K) E8.5 forebrains viewed from the lateral side just after closure of the neural tube, anterior is towards the left. At this stage of telencephalic development in wild-type mice, Nog expression appears in a restricted domain at the anterior dorsal midline (A,I, arrows). In three Emx2 homozygous mutant mice (Emx2^–/–), this domain of Nog expression extends about three times as far posteriorly along the midline (B,J,K). In addition, Nog expression appears stronger than in wild type (arrows in L,M). Mice represented in A and B, I and J, and L and M are paired littermates. No detectable differences were seen in Bmp4 or7 expression (C-F), but BMP activity appears deficient in the Emx2 mutant, assessed by the loss of Msx2 expression (G,H, asterisks). Scale bar: 0.3 mm for A-H; 0.17 mm for I-J; 0.06 mm for L,M.