Larger Image Fig. 3. BMPpathway overactivation affects cell specification in the developing Xenopus epidermis. Stage 9 Xenopus embryos were injected in the blastocoel with either BSA (A-M) or 2-7 ng recombinant BMP4 (A′-M′). (A,A′) SEM of the epidermis at stage 37 revealed the severe decrease in the numbers of MCCs (red arrowhead), ionocytes (yellow arrowhead) and SSCs (green arrowhead). (B,B′) At tailbud (stage 30), BMP4-injected embryos showed normal morphology but substantially fewer α-tubulin-positive MCCs, as revealed by whole-mount in situ hybridisation (WISH). (C,C′) Both the differentiated MCC marker acetylated tubulin (white) and the ionocytemarker foxi1e (green)were lost in sectioned tailbud (stage 25)BMP4-injected embryos. (D,D′)WISHrevealed that the differentiated ionocyte marker v1awas strongly decreased in stage 25BMP4-injectedembryos. (E-F′) The differentiatedSSCsmarkers serotonin (red in E,E′) andtryptophan hydroxylase-1 (tph1, red in F,F′)were lost or strongly decreased in stage 25BMP4-injected embryos. (G,G′) In sections of stage 25BMP4-injected embryos, P63 (white), amarker of the non-intercalatinginner layercells,was lost,whereasthe goblet cellmarker intelectin-1 (green)wasupregulated. otogelin (redin H,H′,J,J′)andtrim29(red in I,I′), two other markers of goblet cells, were unaffected. (K-M′) Stage 14 embryos were analysed by WISH in order to stain MCCs for foxj1 (K,K′), ionocytes for foxi1e (L,L′) and SSCs for foxa1 (M,M′). (B,B′,D-F′,J-M′) Whole-mount embryos; (C,C′,G-I′) cryosectioned embryos. (B-M′) All markers were revealed by chromogenic or fluorescent in situ hybridisation, except for acetylated tubulin, serotonin and P63, which were revealed by immunofluorescence. (C,C′,E-I′) Nuclei were stained with DAPI. (B,B′,D-F′,K-M′) The number of embryos showing the phenotype among the total number of embryos examined is indicated. Image published in: Cibois M et al. (2015) Copyright © 2015. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
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