Fonseca M, dél Río J A, Martínez A, Gómez S, Soriano E
Department of Neuroscience, Faculty of Medicine, University of The Basque Country, Leioa, Spain.
J Comp Neurol. 1995 Oct 9;361(1):177-92. doi: 10.1002/cne.903610114.
The prenatal and postnatal development of calretinin (CR)-containing elements in the neocortex of the rat was analyzed using immunohistochemistry. CR immunoreactivity in the cortical anlage appeared early at embryonic day 14 (E14), with CR-positive neurons located in the primitive plexiform layer and in the emerging subplate and marginal zones. At later prenatal and early postnatal stages, these two layers showed the highest CR immunostaining in the cortex, and large numbers of cell bodies and fibers were immunostained. From postnatal day 3 (P3) onwards, CR immunostaining disappeared progressively from the subplate-layer VIb and the marginal zone-layer I, so that very few cells remained stained in these layers in the adult. In the cortical plate and prospective layers VIa to II-III, CR-positive neurons were seen at prenatal stages, their numbers increasing markedly during the first postnatal week. Most neurons showed undifferentiated nonpyramidal shapes, and matured during the second and third postnatal weeks, when the adult pattern of CR immunostaining was achieved. In addition, some pyramidal-like neurons in the infragranular layers and in layer II-III transiently expressed CR during the postnatal period, most notably between P3 and P12. Colocalization experiments performed at P0-P3 with antibodies against the neurotransmitter gamma-aminobutyric acid (GABA) showed that most nonpyramidal CR-positive neurons in the derivates of the cortical plate were also GABAergic during development. In contrast, large numbers of CR-containing neurons in the subplate and marginal zone were GABA-negative. The present results show that in addition to recording the early development of a subset of nonpyramidal neurons, CR is transiently expressed in certain GABA-negative populations of the subplate and marginal zone, and most likely in pyramidal neurons.
利用免疫组织化学方法分析了大鼠新皮质中含钙视网膜蛋白（CR）成分的产前和产后发育情况。皮质原基中的CR免疫反应性在胚胎第14天（E14）时就早早出现，CR阳性神经元位于原始丛状层以及新出现的亚板层和边缘区。在产前后期和产后早期阶段，这两层在皮质中显示出最高的CR免疫染色，大量细胞体和纤维被免疫染色。从出生后第3天（P3）起，CR免疫染色从亚板层VIb和边缘区层I逐渐消失，因此在成年大鼠的这些层中几乎没有细胞保持染色。在皮质板以及预期的VIa层至II - III层，产前阶段可见CR阳性神经元，其数量在出生后的第一周显著增加。大多数神经元呈现未分化的非锥体形状，并在出生后的第二和第三周成熟，此时达到成年期的CR免疫染色模式。此外，颗粒下层和II - III层中的一些锥体样神经元在出生后期间短暂表达CR，最明显的是在P3和P12之间。在P0 - P3进行的与抗神经递质γ-氨基丁酸（GABA）抗体的共定位实验表明，皮质板衍生物中的大多数非锥体CR阳性神经元在发育过程中也是GABA能的。相比之下，亚板层和边缘区中大量含CR的神经元是GABA阴性的。目前的结果表明，除了记录一部分非锥体神经元的早期发育外，CR在亚板层和边缘区的某些GABA阴性群体中短暂表达，并且很可能在锥体神经元中也有表达。
