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Fig. 2. Darmin is an endoderm-specific marker. Whole-mount in situ hybridization was performed on intact (A, F, G, J, K) or hemisectioned Xenopus embryos (B–E, H, I). (A) Animal view of 4-cell stage embryo; note the lack of maternal transcripts. (B) Internal view of a hemisectioned early gastrula embryo (stage 10); Darmin expression starts in the dorsal vegetal cell mass; the arrowhead indicates the dorsal blastopore lip in this and subsequent panels. (C) Close-up of embryo in (B); note nuclear staining in the yolky endoderm adjacent to invaginating mesoderm of Spemann's organizer. (D) At mid-gastrula (stage 11), Darmin-labeled cells are found throughout the endoderm. (E) Internal view of late gastrula embryo (stage 13) showing increased transcript levels in the endoderm excluding the anterior region; the arrow marks the liver diverticulum, a derivative of the foregut. (F, G) Lateral and dorsal views of late neurula (stage 20) displaying Darmin expression in the midgut. (H) Internal view showing signals in the ventral and lateral walls of the midgut. (I) At early tail bud stage (stage 25), staining in the midgut becomes very abundant. (J, K) Lateral views of advanced tail bud embryos (stages 32 and 40); Darmin expression remains strong in the midgut. |
