Ziller C, Mirabel M A, Vandenbunder B, Fauquet M
Institut d'Embryologie Cellulaire et Moléculaire, CNRS, Nogent sur Marne, France.
Anat Embryol (Berl). 1994 Apr;189(4):307-15. doi: 10.1007/BF00190587.
The initial expression of the gene encoding tyrosine hydroxylase (TH) was studied in the trunk of quail embryos by in situ hybridization. We detected the presence of quail TH mRNA on embryonic day 3.5 (E3.5) in the sympathetic ganglia and aortic plexus, both neural crest derived structures. In contrast, the TH gene was expressed much earlier in the endodermal layer of E2 embryos, i.e. from the 8-somite stage onwards. TH mRNA was found also in the pancreatic bud, an endoderm-derived structure. The TH protein and catecholamines were subsequently looked for in these structures. TH immunoreactivity was found in cells of E2 explanted endoderm, but no catecholamine histofluorescence was observed before or after a few days in culture. TH-positive cells were also detected in cultures of pancreatic rudiments, explanted from E3 to E6 quail embryos. We suggest that the TH-positive cells of the endoderm are the progenitors of the catecholaminergic cells of the pancreas and of the enterochromaffin cells of the gut. The hypothesis that the TH-positive cells of the endoderm are involved in the expression of the catecholaminergic phenotype by neural crest cells is discussed.
通过原位杂交技术，研究了鹌鹑胚胎躯干部位酪氨酸羟化酶（TH）编码基因的初始表达情况。我们在胚胎第3.5天（E3.5）时，在交感神经节和主动脉丛中检测到鹌鹑TH mRNA的存在，这两个结构均来源于神经嵴。相比之下，TH基因在E2胚胎的内胚层中表达要早得多，即从8体节阶段开始。在胰腺芽（一种内胚层衍生结构）中也发现了TH mRNA。随后在这些结构中寻找TH蛋白和儿茶酚胺。在E2期外植的内胚层细胞中发现了TH免疫反应性，但在培养前及培养几天后均未观察到儿茶酚胺组织荧光。在从E3至E�鹌鹑胚胎外植的胰腺原基培养物中也检测到了TH阳性细胞。我们认为，内胚层的TH阳性细胞是胰腺儿茶酚胺能细胞和肠道肠嗜铬细胞的祖细胞。文中还讨论了内胚层的TH阳性细胞参与神经嵴细胞儿茶酚胺能表型表达的假说。
