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. 2008 May 16;4(5):e1000073. doi: 10.1371/journal.pgen.1000073

Figure 1. Early expression of Hoxa13 in the allantois and its derivatives.

Figure 1

(A, B) HOXA13 is expressed in the umbilical arteries which partially stenose (white arrow) in Hoxa13 homozygous mutants. (C) Fluorescent and bright field image of an E7.75 embryo expressing HOXA13-GFP. AL = allantois, CC = cardiac crescent. (D) HOXA13-GFP is expressed throughout the allantois at E8.5. Red signal = detection of the HOXA13-GFP fusion protein using a GFP antibody (denoted as α-GFP). Green signal indicates detection of the endogenous HOXA13-GFP fusion protein. Yellow signal (Merged) indicates the co-localization of the detected HOXA13-GFP protein and the α-GFP immuno-positive cells, confirming the detected green fluorescence to be derived from the mutant HOXA13-GFP fusion protein throughout the allantois. AL = allantois; EM = embryo proper. (E, F) Cryosection of an E9.5 placenta. Green signal indicates detection of the HOXA13-GFP fusion protein in the developing labyrinth region; red signal indicates detection of the HOXA13-GFP fusion protein using a GFP antibody (denoted as α-GFP). Note the absence of HOXA13-GFP expression in the chorionic ectoderm (CE). Arrows denote sites of microvessel genesis. Dashed line represents chorionic plate. AS = allantoic stalk. (G) Sagittal section of an E9.5 embryo and developing placenta. Note that HOXA13-GFP expression is maintained in the allantoic stalk as it contributes to the developing allantoic vessels (arrows) as well as the developing chorionic plate vessels (asterisks). Dashed line denotes the developing chorionic plate. CE = chorionic ectoderm, EM = embryo proper, AS = allantoic stalk. (H) At E10.5, HOXA13 expression is maintained in the developing labyrinth (LAB), whereas little or no expression is detected in the chorionic ectoderm (CE). Bars are 25 µm.