Dávila J C, Padial J, Andreu M J, Guirado S
Departamento de Biología Celular, Facultad de Ciencias, Universidad de Málaga, Spain.
J Comp Neurol. 1999 Mar 1;405(1):61-74.
The morphology, distribution, and ultrastructural features of calbindin-D28k-immunoreactive neurons and fibers in the cortical regions of the lizard Psammodromus algirus, considered homologues to the mammalian hippocampal formation, were analyzed by using the peroxidase anti-peroxidase technique at the light and electron microscopic level. On the basis of staining properties and localization, two distinct populations of calbindin-D28k-immunoreactive neurons were observed in both the medial and dorsal cortices. Those located in the cell layer, namely principal neurons, were weakly immunostained, whereas a number of Golgi-like stained neurons were observed in plexiform layers. Double immunocytochemistry showed that all calbindin immunoreactive neurons in the deep plexiform layers were also gamma-aminobutyric acid immunoreactive. We consider them as a population of nonprincipal neurons different from those containing the calcium-binding proteins parvalbumin and calretinin. Two types of immunoreactive Boutons were revealed by electron microscopy on the basis of the synaptic specialization: Boutons making asymmetrical synapses were generally smaller in size and contacted on small dendritic profiles or cell bodies, whereas larger boutons established symmetrical synapses mainly on dendritic shafts. We propose that the first type of boutons arises from principal neurons and that the second type arises from nonprincipal ones. Finally, the staining pattern, localization, and the circuit in which nonprincipal calbindin-immunoreactive neurons and other neurochemically defined neurons could be involved in cortical regions of Psammodromus are compared with those of mammalian hippocampus.
利用过氧化物酶抗过氧化物酶技术，在光镜和电镜水平上分析了蜥蜴沙蜥（Psammodromus algirus）皮质区域中钙结合蛋白-D28k免疫反应性神经元和纤维的形态、分布及超微结构特征，这些皮质区域被认为与哺乳动物海马结构同源。基于染色特性和定位，在内侧和背侧皮质中均观察到了两个不同的钙结合蛋白-D28k免疫反应性神经元群体。位于细胞层的那些神经元，即主要神经元，免疫染色较弱，而在丛状层中观察到一些呈高尔基样染色的神经元。双重免疫细胞化学显示，深丛状层中所有钙结合蛋白免疫反应性神经元也呈γ-氨基丁酸免疫反应性。我们认为它们是不同于含有钙结合蛋白小白蛋白和钙视网膜蛋白的神经元群体的非主要神经元。基于突触特化，电镜揭示了两种类型的免疫反应性终扣：形成不对称突触的终扣通常较小，与小的树突轮廓或细胞体接触，而较大的终扣主要在树突干上形成对称突触。我们提出，第一种类型的终扣起源于主要神经元，第二种类型起源于非主要神经元。最后，将沙蜥皮质区域中非主要钙结合蛋白免疫反应性神经元和其他神经化学定义的神经元的染色模式、定位以及可能涉及的神经回路与哺乳动物海马的进行了比较。
