FIG. 1. Analysis of the competence of the ectoderm to respond to neural fold and neural plate induction. (a, d– g) Ventral animal caps were taken at different stages as indicated in the figure and combined with a piece of dorsal mesoderm taken from stage 10.5 (yellow in a). The conjugates were cultured until stage 17, fixed, and examined by whole-mount in situ hybridization using an Xslug antisense probe. (d) Stage 10 ectoderm; notice the strong Xslug induction (arrows). (e) Stage 11 ectoderm; notice the Xslug induction (arrows). (f) Stage 12 ectoderm; notice the weak Xslug induction (arrows). (g) Stage 13 ectoderm; no induction was detected, although it should be noticed that this photograph was taken under different magnification and light conditions than in (d–f). (h–k) Similar experiment to that described in (a) but Xsox-2 expression was analyzed. (h) Control embryo showing Xsox-2 expression in the neural plate. (i) Control of ectoderm taken from a stage 10 embryo, cultured in vitro until stage 17, fixed, and analyzed for Xsox-2 expression. No expression was detected. (j) Stage 12 and (k) stage 13 ectoderm; notice the Xsox-2 induction (arrows). (b, l– s) Ventral ectoderm taken from embryos injected with RLDx (magenta in b) and transplanted into stage 13 embryos. The embryos were cultured until stage 17 and analyzed for Xslug expression by whole-mount in situ hybridization. (l–o) Xslug in situ hybridization; (p– s) fluorescent image of the corresponding in situ hybridization shown. Graft of a stage 10 (l, p) or 11 (m, q) ectoderm; note the normal Xslug expression in both neural folds (l, m) and the Xslug expression in the region of the fluorescent transplant (p, q, arrow in l and m). Graft of a stage 12 (n, r) or 13 (o, s) ectoderm; notice the gap of Xslug expression in one of the folds (n, o) and the absence of Xslug expression in the region of the fluorescent transplant (n, r, o, s). (t) Control of ventral ectoderm taken from a stage 10 embryo, cultured in vitro until stage 17, fixed, and analyzed for Xslug expression. No expression was detected. (c, u–w) Ventral ectoderm taken from an embryo previously injected with FLDx (green in c) was transplanted into the prospective folds of a stage 11.5 embryo. The embryo was cultured until stage 17, fixed, analyzed for Xslug expression, and sectioned. Only the transplant of the stage 13 embryo is shown (u); notice the interruption of the Xslug expression in one of the folds (u; arrowhead shows the normal Xslug expression) and the absence of Xslug expression in the region of the fluorescent transplant (v; in w: asterisk, transplanted ectoderm; arrowheads, host’s Xslug expression).
Image published in: Mancilla A and Mayor R (1996)
Copyright © 1996. Image reproduced with permission of the Publisher, Elsevier B. V.
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