Figure 2

Distribution of Cubilin protein in primitive endoderm cellular derivatives from postimplantation E5.5 to E8.5. Whole mount image of immunofluorescence for Cubilin (red) in Afp-GFP VE reporter embryo (green). (A–A”) At E5.5, Cubilin is expressed by VE cells (A) while GFP is detected exclusively in the emVE (A’). All GFP positive cells express Cubilin. (A”) Inset shows Cubilin expression in emVE cells. (B–B”) By E6.5, at the onset of gastrulation, Cubilin is strongly expressed by exVE cells. (B) GFP expression spread more proximally into the exVE (B’). All GFP positive cells express Cubilin (B”) in emVE. (C–C”) At E7.5, late bud/early head fold stage, Cubilin is expressed throughout the exVE and in dispersed emVE cells. (C) All GFP cells express Cubilin (C’,C”). Inset shows Cubilin expression in squamous emVE cells. (D–D’) At E8.5 (5–6 somites stage), Cubilin is expressed strongly in the visceral yolk sac (vys), and the dispersed emVE cells. (D) Cubilin expression domain matches integrally with this of GFP (D’,D”). emVE: embryonic visceral endoderm, exVE: extraembryonic visceral endoderm, n: node, ps: primitive streak. Scale bars: 20 μm.