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. Author manuscript; available in PMC: 2012 Jan 24.
Published in final edited form as: Dev Dyn. 2011 Sep;240(9):2175–2193. doi: 10.1002/dvdy.22711

Fig. 2. Localization of hedgehog signaling components: Phase I (Neural plate/no allantoic bud (OB)- Headfold (HF) stages, ~7.0–8.0 dpc).

Fig. 2

In this and all figures, stages are indicated in the lower left; unstaged panels correspond to the last indicated stage. All orientations are sagittal, with anterior on the left, and posterior on the right. In this and all figures, the proteins analyzed are indicated in the lower right of panels; unlabeled panels correspond to the last indicated gene product. (A, B) Neural plate/No allantoic bud (OB) stage (~7.0 dpc), Ptc-1 (royal blue color). Whole mount (A) and sectioned (B) specimens. Arrowhead (A) indicates the node, which, at this stage, does not exhibit perceptible Ptc-1 when examined in section (also compare this whole mount specimen with the node in panel C, arrowhead). White arrowheads bracket the Ptc-1-positive embryonic/extraembryonic junction that is enlarged in B. al, allantois; am, amnion; ch, chorion, pat, proamniotic tube; ys, visceral yolk sac. (C–E) Neural plate/Early bud (EB) stage (~7.25 dpc), Ptc-1. Whole mount (C) and sectioned (D, E) specimens. Note the presence of Ptc-1 in the node (arrowheads, C, D); arrow (E) indicates Ptc-1-positive presumptive VCM on the allantois (al); asterisk (E) indicates the allantoic core domain (ACD). (F, G), Early headfold (EHF) stage (~7.75 dpc), Ptc-1. Whole mount (F) and sectioned (G) specimens. Placement of the arrow (G) indicates the VCM and its association with the visceral yolk sac; asterisk indicates the ACD. d, dorsal cuboidal mesothelium (DCM, see text). Note the low-level of Ptc-1 in the allantois-associated extraembryonic visceral endoderm (ax). (H, I) EHF stage, Smoothened (Smo), sectioned specimen. Note in (H) that Smo is found throughout the visceral endoderm, both embryonic and extraembryonic, and associated underlying cells, several layers thick, as well as in the ventral node (arrowhead, H) and notochord and VCM of the allantois, seen at higher magnification in (I) (arrow). (J, K) EHF stage, Sonic hedgehog (Shh) IHC, sectioned specimen. Note in (J) that, like Smo, Shh localizes to the visceral endoderm, both embryonic and extraembryonic, and several underlying cell layers, as well as to the ventral node (arrowhead, J) and notochord, and VCM of the allantois, seen at higher magnification in (K), arrow, at its intersection with the visceral yolk sac (ys). (L, M) EHF stage, Indian hedgehog (Ihh) sectioned specimen. Comparison of Ihh with Smo and Shh reveals that Ihh is less intense in the visceral endoderm and VCM (arrow, M). (N, O) EHF stage, Ptc-1 (N) is found in both dorsal (d) and ventral (v) layers of the node; for reasons that are unclear, Smo (O) localizes to the ventral layer only. The small arrows in each panel indicate the notochord. (P–S) Series of sections of presumptive intraplacental yolk sac in the chorionic ectoderm (ce) and visceral yolk sac (ys). Arrowheads indicate Ptc-1 (arrowheads, P, Q), Smo (arrowhead, R), and Shh (arrowhead, S) in this region. Scale bar (S): 50 μm (E, G, P-R); 35 μm (I, K, M-O, S); 140 μm (H, J, L); 100 μm (B, D); 400 μm (A, C, F).