Fig. 1. Effect of ventral tBR injection on whole embryos and explanted ventral marginal zones. (A-C) Uninjected embryos. (D-F) Embryos injected ventrally with tBR RNA. (A,D) Dorsal view of tadpoles. (B,E) Transverse sections through tadpoles. (C,F) Immunostaining of the notochord with the monoclonal antibody MZ15 (the otic vesicle is also labelled with MZ15). (G-I) Ventral marginal zone explants differentiate into notochord in the absence of BMP signals. Dorsal (G) or ventral (H,I) marginal zones were isolated at early gastrula stage from uninjected embryos (G,H) or embryos injected ventrally with tBR RNA (I). Explants were cultured until stage 23, and immunostained with MZ15.
