Regional specification of the endoderm in the early chick embryo.
In the avian embryo, the endoderm, which forms a simple flat-sheet structure after gastrulation, is regionally specified in a gradual manner along the antero-posterior and dorso-ventral axes, and eventually differentiates into specific organs with defined morphologies and gene expression profiles. In our study, we carried out transplantation experiments using early chick embryos to elucidate the timing of fate establishment in the endoderm. We showed that at stage 5, posteriorly grafted presumptive foregut endoderm expressed CdxA, a posterior endoderm marker, but not cSox2, an anterior endoderm marker. Conversely, anteriorly grafted presumptive mid-hindgut endoderm expressed cSox2 but not CdxA. At stage 8, posteriorly grafted presumptive foregut endoderm also expressed CdxA and not cSox2, but anteriorly grafted presumptive mid-hindgut endoderm showed no changes in its posterior-specific gene expression pattern. At stage 10, both posteriorly grafted foregut endoderm and anteriorly grafted mid-hindgut endoderm maintain their original gene expression patterns. These results suggest that the regional specification of the endoderm occurs between stages 8 and 10 in the foregut, and between stages 5 and 8 in the mid-hindgut.
Kimura
Wataru
W
Department of Biological Science, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.
Yasugi
Sadao
S
Fukuda
Kimiko
K
D000818:Animals; D030161:Avian Proteins / Q000235:genetics; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000235:genetics; D004064:Digestive System / Q000196:embryology / Q000378:metabolism; D047108:Embryonic Development; D004707:Endoderm / Q000166:cytology* / Q000378:metabolism* / Q000637:transplantation; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D024002:HMGB Proteins / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D017403:In Situ Hybridization; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors / Q000235:genetics; D016042:Transplantation, Heterotopic
D030161:Avian Proteins; C084100:CdxA protein, Gallus gallus; D004268:DNA-Binding Proteins; D024002:HMGB Proteins; D018398:Homeodomain Proteins; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors