Peters-van der Sanden M J, Kirby M L, Gittenberger-de Groot A, Tibboel D, Mulder M P, Meijers C
Department of Anatomy, Medical College of Georgia, Augusta.
Dev Dyn. 1993 Mar;196(3):183-94. doi: 10.1002/aja.1001960305.
The vagal neural crest adjacent to the first seven somites gives rise to both ganglionic and ectomesenchymal derivatives. Ganglionic derivatives are the neurons and supportive cells of the enteric nervous system (ENS), cardiac, and dorsal root ganglia. Ectomesenchymal derivatives are cells in the cardiac outflow tract and the mesenchymal components of thymus and parathyroids. Ectomesenchymal derivatives are formed by a segment of the vagal neural crest, from the level of the otic vesicle down to the caudal boundary of the third somite, called the cardiac neural crest. We performed neural crest ablations to study regional differences within the avian vagal neural crest with regard to the formation of the ENS. Ablation of the entire vagal neural crest from the mid-otic vesicle down to the seventh somite plus the nodose placode resulted in the absence of ganglia in the midgut (jejunum and ileum) and hindgut (colon). The foregut (esophagus, proventriculus, gizzard, and duodenum) was normally innervated. After ablation of the vagal neural crest adjacent to somites 3-5, ganglia were absent in the hindgut. Ablations of vagal neural crest not including this segment had no effect on the formation of the ENS. We surmise that the innervation of the hindgut in vivo depends specifically on the neural crest adjacent to somites 3-5, whereas innervation of the midgut can be accomplished by all segments within the vagal neural crest. The foregut can also be innervated by a source outside the vagal neural crest. To study intrinsic differences between various vagal neural crest segments regarding ENS formation, we performed chorioallantoic membrane cocultures of segments of quail vagal neural anlage and E4 chicken hindgut. We found that all vagal neural crest segments were able to give rise to enteric ganglia in the hindgut. When the neural crest of somites 6 and 7 was included in the segment, we also found melanocytes in the hindgut, suggesting that this segment is more related to trunk neural crest. Furthermore, we found that the vagal neural anlage from older embryos (> 18 somites) showed an increased potential to form enteric ganglia. This suggests that vagal neural crest cells that have been in prolonged contact with the neural tube in vivo, because of either late emigration or delayed migration, have an increased probability to form enteric ganglia.
与前七个体节相邻的迷走神经嵴产生神经节和外胚间充质衍生物。神经节衍生物是肠神经系统（ENS）、心脏和背根神经节的神经元及支持细胞。外胚间充质衍生物是心脏流出道以及胸腺和甲状旁腺的间充质成分中的细胞。外胚间充质衍生物由迷走神经嵴的一段形成，从耳泡水平向下至第三体节的尾侧边界，称为心脏神经嵴。我们进行了神经嵴消融实验，以研究鸟类迷走神经嵴内关于ENS形成的区域差异。从耳泡中部向下至第七体节加上结状原基进行整个迷走神经嵴的消融，导致中肠（空肠和回肠）和后肠（结肠）中神经节缺失。前肠（食管、腺胃、肌胃和十二指肠）的神经支配正常。在消融与第3 - 5体节相邻的迷走神经嵴后，后肠中神经节缺失。不包括该节段的迷走神经嵴消融对ENS的形成没有影响。我们推测，体内后肠的神经支配特别依赖于与第3 - 5体节相邻的神经嵴，而中肠的神经支配可由迷走神经嵴内的所有节段完成。前肠也可由迷走神经嵴外的来源进行神经支配。为了研究迷走神经嵴不同节段在ENS形成方面的内在差异，我们进行了鹌鹑迷走神经原基节段与E4鸡后肠的绒毛尿囊膜共培养实验。我们发现所有迷走神经嵴节段都能够在后肠中产生肠神经节。当该节段包含第6和7体节的神经嵴时，我们在后肠中还发现了黑素细胞，这表明该节段与躯干神经嵴的关系更为密切。此外，我们发现来自较老胚胎（> 18个体节）的迷走神经原基形成肠神经节的潜力增加。这表明，由于迁出较晚或迁移延迟而在体内与神经管长时间接触的迷走神经嵴细胞形成肠神经节的概率增加。
