Fig. 2. Expression of XGrhl1 is restricted to tissues with an epidermal fate. Whole-mount in situ hybridization analysis of XGrhl1 expression in staged embryos. Maternal XGrhl1 transcripts are detected in the animal pole of early cleavage (A), blastula (B-D) and gastrula (E-H) stage embryos. Embryos are in a lateral orientation except for F (dorsal) and G (ventral). Zygotic expression is observed in presumptive epidermis through neurulation (I-L; dorsal orientation), tailbud and swimming tadpole stages (Q and R respectively; lateral orientation, anterior towards the left). Transverse embryonic section at stage 15 (M) demonstrates XGrhl1 expression (blue stain) in the presumptive epidermis, this stain being absent from the neural plate (arrowhead). By stage 21 (P), the neural plate is closed and covered by epidermis. Epidermal keratin (XK81A1) and zygotic XGrhl1 have a similar pattern of expression (N,O; anterior and dorsal orientation, respectively).