Stolle Ilse
Zoologisches Institut der Universität Bonn, Deutschland.
Wilhelm Roux Arch Entwickl Mech Org. 1968 Mar;161(1):30-48. doi: 10.1007/BF00575215.
Silkies differ from Brown Leghorns not only in their plumage but also in the pigmentation of their connective tissue. The Silky fowl has intensely pigmented tissue in contrast to the Brown Leghorn. The pigmentation of the connective tissue depends on a sex-linked pair of genes (Dd) as well as a pair of genes with an intermediary effect (Pp). As the effect of those gens turns out to be only quantitative the melanocytes can be evaluated in the connected tissue of the embryos of Silkies, Brown Leghorns and the reciprocal hybrids. The result is an exact description of position and distribution of the melanocytes in the tissue.All the hybrids of Silkies and Brown Leghorns have less pigment than the Silkies, but more than the Brown Leghorns. The male hybrids (PpDd) are pigmented intermediary, whereas the female hybrids have a more (Ppd-) or less (PpD-) intense pigmentation in the internal parts of their body. Up to the 7th embryonic day extension and differentiation of the pigment cells are similar in all the breeds. The hybrids (PpD- and PpDd), however, have fewer pigment cells than the Silky fowl from the beginning.During the 8th or 9th embryonic day a distinct process of degeneration of melanocytes is developing in the Brown Leghorns and the PpD-hybrids. This process, however, cannot be observed in the Silky fowl and the hybrids with the gen combination Dd, dd, d-. This degeneration of melanocytes is caused by the gen D becoming effective rather later and being not or slightly dominant over its allel d.The periodic deviation in the process of melanocytes differentiation depends on the growth rate of the embryos. The maxima of the melanocytes differentiation correspond to the period of a minimum growth.
丝羽乌骨鸡与白来航鸡的不同之处不仅在于它们的羽毛，还在于其结缔组织的色素沉着。与白来航鸡相比，丝羽乌骨鸡的组织色素沉着强烈。结缔组织的色素沉着取决于一对性连锁基因（Dd）以及一对具有中间效应的基因（Pp）。由于这些基因的作用仅为数量上的，因此可以在丝羽乌骨鸡、白来航鸡及其正反交杂种胚胎的结缔组织中评估黑素细胞。结果是对黑素细胞在组织中的位置和分布的精确描述。丝羽乌骨鸡和白来航鸡的所有杂种色素沉着都比丝羽乌骨鸡少，但比白来航鸡多。雄性杂种（PpDd）色素沉着处于中间水平，而雌性杂种在其身体内部的色素沉着较强（Ppd-）或较弱（PpD-）。在胚胎发育的第7天之前，所有品种中色素细胞的扩展和分化都是相似的。然而，杂种（PpD-和PpDd）从一开始就比丝羽乌骨鸡的色素细胞少。在胚胎发育的第8天或第9天，白来航鸡和PpD-杂种中黑素细胞出现明显的退化过程。然而，在丝羽乌骨鸡以及具有基因组合Dd、dd、d-的杂种中未观察到这种过程。黑素细胞的这种退化是由于基因D起效较晚且对其等位基因d无或仅有轻微显性作用所致。黑素细胞分化过程中的周期性偏差取决于胚胎的生长速度。黑素细胞分化的最大值对应于生长最小值的时期。
