Expression profiles of eng3 and pax2a in mgo mutants. Dorsal views (A, G, M, S) of embryos with anterior at the top; lateral views (B-F, H-L, N-R, and T-X) with anterior to the left. A-L: Analysis of eng3 expression in wild-type (A-F) and mgo homozygous mutants (G-L). eng3 expression was not observed in mgo mutants from the 1- to 3-somite stage (G and H). However, weak eng3 expression did initiate around the 5-somite stage (I) in mgo mutants and remained in the dorsal region at the 9-somite stage (J). Later, reduced expression was detected in both the dorsal and ventral region at the 15-somite stage (K). Expression within the dorsal region disappeared while weak expression remained in the ventral region in the 20-somite stage (L). M-X: pax2a expression in wild-type (P-R) and mgo (V-X) mutants. Expression of pax2a was initiated within the MHB primordia at 80-90% epiboly (M,S) and was consistant at the 3- and 5-somite stages (N,O,T,U). By the 9-somite stage, pax2a expression started to decrease in mgo mutants and remained weak at the 15-somite stage (V,W). pax2a expression was completely eliminated by the 20-somite stage (X). Developmental stage and genotype are indicated in the bottom and top right-hand corner of each image, respectively. mgo mutant MHBs are shown by open arrowheads.
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