Tucker R P, Erickson C A
J Exp Zool. 1986 Nov;240(2):173-82. doi: 10.1002/jez.1402400205.
Neural crest-derived melanophores form species-specific patterns in the dermis of amphibian embryos. Melanophore patterns may be generated by one of two general mechanisms: pigment cell precursors disperse throughout the embryo, with melanophores differentiating in certain regions due to environmental cues, or melanoblasts may localize in different regions as a result of a hierarchy of tissue affinities. Both of these mechanisms have been proposed to be responsible for the dorso-ventral patterning of melanophores in Xenopus laevis. We have reexamined the distribution of melanoblasts in X. laevis and Taricha torosa using the dopa (3,4-dihydroxyphenyl-alanine)-staining technique. We have found that many of the dopa-positive cells identified as melanoblasts by some researchers are actually not derived from the neural crest: dopa-positive cells in T. torosa were identified in the transmission electron microscope to be either leukocytes or erythrocytes, in X. laevis dopa-positive cells are found between the ectoderm and somites where neural crest cells are not found, and X. laevis embryos surgically depleted of neural crest have dopa-staining patterns identical to control embryos. Melanoblasts are apparently not found in the ventralmost regions of early T. torosa and X. laevis embryos, providing additional evidence for the role of differential tissue affinities in directing the formation of embryonic pigment cell patterns.
神经嵴衍生的黑素细胞在两栖动物胚胎的真皮中形成物种特异性模式。黑素细胞模式可能由两种一般机制之一产生：色素细胞前体分散在整个胚胎中，黑素细胞由于环境线索在某些区域分化，或者成黑素细胞可能由于组织亲和力层次而定位在不同区域。这两种机制都被认为是非洲爪蟾黑素细胞背腹模式形成的原因。我们使用多巴（3,4-二羟基苯丙氨酸）染色技术重新检查了非洲爪蟾和粗皮渍螈中成黑素细胞的分布。我们发现，一些研究人员鉴定为成黑素细胞的许多多巴阳性细胞实际上并非源自神经嵴：在透射电子显微镜下，粗皮渍螈中的多巴阳性细胞被鉴定为白细胞或红细胞，在非洲爪蟾中，多巴阳性细胞在外胚层和体节之间被发现，而此处没有神经嵴细胞，并且通过手术去除神经嵴的非洲爪蟾胚胎具有与对照胚胎相同的多巴染色模式。在早期粗皮渍螈和非洲爪蟾胚胎的最腹侧区域显然没有发现成黑素细胞，这为差异组织亲和力在指导胚胎色素细胞模式形成中的作用提供了额外证据。
