||Fig. 4. Distribution of XMHCa mRNA in Xenopus embryos. Whole-mount in situ hybridisation was used to examine the spatial
distribution of XMHCa transcripts in tailbud and tadpole embryos. Specific staining (purple) is readily distinguished from the natural
pigmentation (brown/black) of the embryos. (A) Developmental series comprising (from top to bottom) embryo stages 29, 35 and 38.
Staining for XMHCa can be seen in the ventral region immediately anterior to the gut. This corresponds to the developing heart anlage.
(B) Anterior region of a stage 35 tadpole. XMHCa expression is clearly restricted to the conus arteriosus, heart chambers and sinus
venosus that have formed from the endocardial tube.