Fig. 6. Npnt is widely expressed during development. (A) Npnt WISH shows strong expression in neural tissue and axial mesoderm in the late neurula (stage 19). (B) Tailbud (stage 30) and tadpole (C, stage 39) express in the head/gill arches, CNS, somites, and pronephros (arrow). (DâF) Transverse sections of npnt WISH at stages 46â49 show broad staining including pronephros (black arrow) but exclusion from the epidermis and the prospective forelimb-forming region (open arrow).