PMC

Whole mount in situ hybridization of Wnt genes with ectodermal localization in the more anterior domain of the embryo. All data are presented as optical sagittal or frontal sections following clearing in Murray Clear. Developmental staging is from blastula to 72 h of development. All embryos are oriented with anterior, or animal (in the case of blastula), to the top left of the panel and posterior, or vegetal, to the bottom right of the panel. Right column, ventral is to the bottom left. Unless otherwise noted, expression is ectodermal. (Ai-Av), Expression of wnt8 at blastula stage (Ai), midgastrula stage (Aii), 30 h (Aiii), 50 h, side view (Aiv), and 72 h of development, side view (Av). (Bi-Bv), Expression of wnt 2. Blastula stage (Bi), at late gastrula (Bii), at 36 h (Biii), at 48 h, frontal view (Biv), and at 72 h of development, side view (Bv). (Ci-Cv), Expression of wnt11 at blastula stage (Ci), at gastrula stage (Cii), at 48 h, side view (Ciii), 60 h, side view (Civ), and 72 h of development, side view. (Di-Dv), Expression of wnt7 at blastula stage (Di), gastrula stage (Dii), 36 h (Diii), 48 h, showing a dorsal view with focal plane through the dorsal ectoderm (Div), and 72 h of development, side view (Dv). (Ei-Ev), Expression of wnt5 at blastula stage (Ei), at midgastrula stage (Eii), at 48 h, dorsal view (Eiii), at 60 h, side view (Eiv), and at 72 h of development in side view (Ev). (Fi-Fv), Expression of wntA, no expression for the first 48 h at blastula stage (Fi), gastrula stage (Fii), and at 40 h of development (Fiii). Expression begins at 48 h shown as a frontal section from a dorsal view (Fiv), and at 72 h of development with a side view (Fv). (Gi-Gv), Expression of wnt9 at blastula stage (Gi), at midgastrula stage (Gii), at 48 h, showing a ventral view with optical section through the ventral ectoderm and posterior mesoderm (Giii), at 60 h of development again in ventral view (Giv), and at the same stage in side view (Gv).

Dynamic spatial gene expression patterns and territories of the oral ectoderm. A) Expression of pax4l, ets4, sip1 and emx. pax4l transcripts are localized in the oral ectoderm during the blastula stage, similar to nodal. Initially ets4, sip1, and emx transcripts cover both oral and aboral ectoderm. Oral expression of these genes fades at mid-blastula and becomes complementary to the central oral ectoderm (marked by lefty expression in the double WMISH) after18 h. B) Diagrams illustrating ectodermal gene expression domains shown in lateral view. Developmental stages are the early blastula stage (12h), late blastula stage (18h), and mesenchyme blastula stage (24h). For simplicity, endomesodermal domains are not indicated. Ectodermal domains are color-coded and labeled on the left; domain-specific genes are shown in . Apical—apical plate; Ec—ectoderm. lv—lateral view; vv—vegetal view; av—apical view. All embryos in lateral or vegetal views were shown with the oral ectoderm facing left. C) Expression matrix for ectodermal genes during the blastula stage. Three time points were included representing the early blastula stage (12h), late blastula stage (18h), and mesenchyme blastula stage (24h). A graphic presentation of the expression patterns is shown in .

(A) In situ hybridization examining FGFR4 expression in wildtype Xenopus embryos collected at blastula (stage 9, lateral view, animal pole up), late gastrula (stage 12, dorsal view, anterior up), and mid-neurula (stage 15, dorsal view, anterior up) stages. Expression is seen in the pluripotent cells of the animal hemisphere at blastula stages and in the neural plate and neural crest forming regions at gastrula and neurula states. (B) Animal pole explant assay examining FGFR4 expression. Explants were cultured alongside sibling embryos and collected at blastula (stage 9), late gastrula (stage 12), and mid-neurula (stage 15) stages. (C) In situ hybridization examining Vent2, Id3, Myc, and FoxD3 expression in blastula stage (stage 9) embryos injected with dominant-negative FGFR4 (dnFGFR4). Asterisk denotes injected side, marked by staining of the lineage tracer β-galactosidase (red). Dominant-negative FGFR4 blocks expression of Vent2 and Id3.

In A. filiformis hesC is co-expressed with its immediate downstream genes. a Single WMISH for blastula and mesenchyme blastula stage embryos. b Double fluorescent WMISH on blastula stage embryos. Afi-hesC expression is restricted to a ring of cells in the vegetal half and co-expressed with the endomesodermal marker Afi-foxA. Afi-ets1/2, Afi-tbr, and Afi-delta are co-expressed with Afi-hesC in one cell layer (yellow area) at the vegetal plate of the embryo at blastula stage and completely co-expressed at mesenchyme blastula stage. VV vegetal view, SVV semi vegetal view, Bl blastula, MBl mesenchyme blastula