Payette R F, Tennyson V M, Pomeranz H D, Pham T D, Rothman T P, Gershon M D
Department of Anatomy and Cell Biology, College of Physicians and Surgeons of Columbia University, New York, New York 10032.
Dev Biol. 1988 Feb;125(2):341-60. doi: 10.1016/0012-1606(88)90217-5.
Aganglionosis occurs in the terminal colon of the ls/ls mouse because an intrinsic defect of the presumptive aganglionic tissue prevents the entry and colonization of this portion of the bowel by migrating neural crest cells. The current study was undertaken to determine if abnormalities of the extracellular matrix could be identified in this segment that might account for migratory failure. Since basal laminae of the muscularis mucosa are overproduced in the aganglionic segment of adult ls/ls mice, we examined components of basal laminae in fetal gut from Day E 11 to Day E 16 of gestation. This period spans the time of enteric ganglion formation. Laminin and collagen type IV were studied by immunocytochemistry and proteoglycans by staining glycosaminoglycans with Alcian blue. Abnormalities of each of these components occur during development of the presumptive aganglionic bowel in the ls/ls mouse and could be detected as early as Day E 11. These defects consist mainly of an overabundance of these materials, both in defined basal laminae and throughout the extracellular space of the mesenchyme. Electron microscopic observations in the presumptive aganglionic ls/ls colon revealed a thickening of basal laminae and exceptionally wide intercellular spaces between smooth muscle myoblasts that contained an irregular fibrillar material, consisting of 4.5- to 6.0-nm filaments associated with 14- to 20-nm granules. Fibrillar and flocculant material was continuous with formed basal laminae, and was concentrated in the same areas found to have an overabundance of laminin immunoreactivity. These observations indicate that there is an accumulation of extracellular matrix material, including components of basal laminae, that (i) precedes the formation of enteric ganglia, (ii) is in the path through which enteric neural precursors from the crest would have to migrate, and (iii) is limited to the aganglionic and hypoganglionic ls/ls bowel. These data are consistent with the hypothesis that components of basal laminae contribute to the inability of crest cells to colonize the terminal bowel of ls/ls mice.
无神经节症发生在ls/ls小鼠的终末结肠，因为假定的无神经节组织的内在缺陷阻止了迁移的神经嵴细胞进入该部分肠道并在其中定植。当前的研究旨在确定在该节段中是否能识别出细胞外基质的异常，这可能是迁移失败的原因。由于成年ls/ls小鼠无神经节段的黏膜肌层基底层过度产生，我们检查了妊娠第E11天至第E16天胎儿肠道基底层的成分。这个时期涵盖了肠神经节形成的时间。通过免疫细胞化学研究层粘连蛋白和IV型胶原，并用阿尔辛蓝染色糖胺聚糖来研究蛋白聚糖。在ls/ls小鼠假定的无神经节肠道发育过程中，这些成分中的每一种都会出现异常，并且早在第E11天就可以检测到。这些缺陷主要包括这些物质在确定的基底层以及间充质的整个细胞外空间中过量。对假定的无神经节ls/ls结肠的电子显微镜观察显示，基底层增厚，平滑肌成肌细胞之间的细胞间隙异常宽阔，其中含有不规则的纤维状物质，由4.5至6.0纳米的细丝与14至20纳米的颗粒相关联组成。纤维状和絮凝状物质与形成的基底层连续，并集中在发现层粘连蛋白免疫反应性过量的相同区域。这些观察结果表明，存在细胞外基质物质的积累，包括基底层的成分，（i）在肠神经节形成之前，（ii）在来自嵴的肠神经前体必须迁移的路径中，并且（iii）仅限于无神经节和神经节减少的ls/ls肠道。这些数据与基底层成分导致嵴细胞无法在ls/ls小鼠的终末肠道定植的假设一致。
