Izaguirre M F, Soler A P, Casco V H
Laboratorio de Microscopía, Facultad de Ingeniería-Bioingeniería (UNER), Parana, Entre Ríos, Argentina.
Eur J Histochem. 2000;44(4):407-18.
Cadherins and N-CAM are Ca++-dependent and Ca++-independent cell adhesion molecules respectively. These molecules play a key role in morphogenesis and histogenesis. We determined the spatiotemporal pattern of N-cadherin and N-CAM-180 kDa expression by immunohistochemistry during development in two South-American anuran species (Bufo arenarum, toad and Hyla nana, frog). Both N-cadherin and N-CAM were not detectable during early developmental stages. Expression of N-cadherin appeared between the inner and the outer ectoderm layers at stages 19-20. At stages 24-25, N-cadherin was expressed in the neural tube and the heart. In early tadpoles, N-cadherin expression increased along with the central nervous system (CNS) morphogenesis, and reached its maximum level at metamorphic climax stage. N-Cadherin expression was not uniformly distributed. At stage 42, olfactory placodes and retina expressed N-cadherin. Contrary to N-CAM, the strongly myelinated cranial nerves were not labeled. N-Cadherin was present in several mesoderm derivatives such as the notochord, heart and skeletal muscle. The non-neural ectoderm and the endoderm were always negative. Expression of N-CAM appeared first in the neural tube at stages 24-25 and the level of expression became uniform from pre-metamorphic to metamorphic climax tadpoles. At this latter stage, a clear N-CAM immunolabeling appeared in the nerve terminals of pharynx and heart. N-Cadherin and N-CAM were found mainly co-expressed in the CNS from early tadpole to metamorphic climax tadpole. Our results show that the expression of N-CAM and N-cadherin is evolutionary conserved. Their increased expression during late developmental stages suggests that N-CAM and N-cadherin are involved in cell contact stabilization during tissue formation.
钙黏着蛋白和神经细胞黏附分子（N-CAM）分别是依赖钙离子和不依赖钙离子的细胞黏附分子。这些分子在形态发生和组织发生过程中发挥着关键作用。我们通过免疫组织化学方法，确定了两种南美无尾两栖类动物（海滨蟾蜍和纳氏树蛙）发育过程中N-钙黏着蛋白和180 kDa N-CAM的时空表达模式。在发育早期阶段，N-钙黏着蛋白和N-CAM均无法检测到。N-钙黏着蛋白的表达在第19-20阶段出现在内外胚层之间。在第24-25阶段，N-钙黏着蛋白在神经管和心脏中表达。在早期蝌蚪中，N-钙黏着蛋白的表达随着中枢神经系统（CNS）的形态发生而增加，并在变态高潮期达到最高水平。N-钙黏着蛋白的表达并非均匀分布。在第42阶段，嗅基板和视网膜表达N-钙黏着蛋白。与N-CAM相反，强髓鞘化的脑神经未被标记。N-钙黏着蛋白存在于几种中胚层衍生物中，如脊索、心脏和骨骼肌。非神经外胚层和内胚层始终呈阴性。N-CAM的表达首先在第24-25阶段出现在神经管中，从变态前到变态高潮期蝌蚪，其表达水平变得均匀。在后期这个阶段，在咽部和心脏的神经末梢出现了明显的N-CAM免疫标记。从早期蝌蚪到变态高潮期蝌蚪，N-钙黏着蛋白和N-CAM主要在中枢神经系统中共表达。我们的结果表明，N-CAM和N-钙黏着蛋白的表达在进化上是保守的。它们在发育后期阶段表达增加，表明N-CAM和N-钙黏着蛋白参与了组织形成过程中的细胞接触稳定。
