Carlson B M
Department of Anatomy, University of Michigan, Ann Arbor 48109.
Am J Anat. 1988 May;182(1):96-105. doi: 10.1002/aja.1001820109.
Supernumerary wing structures are readily produced by grafting pieces of wing-bud mesoderm into different locations of host wing buds, but the mechanism underlying their formation remains obscure. The major aim of this study was to examine the ability of posterior quail wing-bud mesoderm, cultured in vitro long enough to lose ZPA (zone of polarizing activity) activity, to stimulate or participate in the formation of supernumerary structures when grafted into anterior slits of host chick wing buds. Small pieces of anterior and posterior quail wing-bud mesoderm (HH stages 21-23) were placed in in vitro culture for up to 3 days. After 2 days, ZPA activity of cultured mesoderm was lost. After the grafting of 2- to 3-day cultured anterior quail wing-bud mesoderm into posterior slits of host chick wing-buds, a consistently high percentage (70%-90%) of grafts result in formation of supernumerary cartilage; in this experiment, however, only a low percentage of grafts resulted in supernumerary cartilage when 2- to 3-day cultured posterior mesoderm was grafted into anterior slits. Taken with controls, these results show that positional differences exist between cultured anterior and posterior wing-bud mesoderm. Serial-section analysis of numerous operated wings has shown several patterns of contribution to supernumerary structures by cells of graft and host. Single supernumerary digits induced by grafts of ZPA mesoderm into anterior slits were normally composed entirely of host cells, but graft cells regularly contributed to skeletal elements of more complex supernumerary structures. Cartilage rods produced by anterior-to-posterior grafts were composed mostly of graft cells, but cartilage nodules and the bases of some rods were often mosaics of chick and quail cells. The results support the proposition that mesodermal cells of the quail wing-bud possess a form of anteroposterior positional memory, but its nature and the means by which the memory of grafted cells interacts with host mesoderm are still not clear.
通过将翅芽中胚层片段移植到宿主翅芽的不同位置，很容易产生额外的翅结构，但它们形成的潜在机制仍不清楚。本研究的主要目的是检测体外培养足够长时间以丧失极化活性区（ZPA）活性的鹌鹑后翅芽中胚层，在移植到宿主鸡胚翅芽的前缝时刺激或参与额外结构形成的能力。将小块鹌鹑前、后翅芽中胚层（HH第21-23期）置于体外培养长达3天。2天后，培养的中胚层丧失ZPA活性。将培养2-3天的鹌鹑前翅芽中胚层移植到宿主鸡胚翅芽的后缝后，相当高比例（70%-90%）的移植会导致额外软骨的形成；然而，在本实验中，当将培养2-3天的后中胚层移植到前缝时，只有低比例的移植导致额外软骨的形成。与对照结果相结合，这些结果表明培养的前、后翅芽中胚层之间存在位置差异。对大量手术翅膀的连续切片分析显示了移植细胞和宿主细胞对额外结构的几种贡献模式。将ZPA中胚层移植到前缝诱导的单个额外指通常完全由宿主细胞组成，但移植细胞经常对更复杂额外结构的骨骼成分有贡献。前后移植产生的软骨棒主要由移植细胞组成，但软骨结节和一些棒的基部通常是鸡和鹌鹑细胞的嵌合体。这些结果支持这样的观点，即鹌鹑翅芽的中胚层细胞具有一种前后位置记忆形式，但其性质以及移植细胞的记忆与宿主中胚层相互作用的方式仍不清楚。
