Berki A C, O'Donovan M J, Antal M
Department of Anatomy, University Medical School, Debrecen, Hungary.
J Comp Neurol. 1995 Nov 27;362(4):583-96. doi: 10.1002/cne.903620411.
The development of immunoreactivity for the putative inhibitory amino acid neurotransmitter glycine was investigated in the embryonic and posthatched chick lumbosacral spinal cord by using postembedding immunocytochemical methods. Glycine immunoreactive perikarya were first observed at embryonic day 8 (E8) both in the dorsal and ventral gray matters. The number of immunostained neurons sharply increased by E10 and was gradually augmented further at later developmental stages. The general pattern of glycine immunoreactivity characteristic of mature animals had been achieved by E12 and was only slightly altered afterward. Most of the immunostained neurons were located in the presumptive deep dorsal horn (laminae IV-VI) and lamina VII, although glycine-immunoreactive neurons were scattered throughout the entire extent of the spinal gray matter. By using some of our previously obtained and published data concerning the development of gamma-aminobutyric acid (GABA)-ergic neurons in the embryonic chick lumbosacral spinal cord, we have compared the numbers, sizes, and distribution of glycine- and GABA-immunoreactive spinal neurons at various developmental stages and found the following marked differences in the developmental characteristics of these two populations of putative inhibitory interneurons. (i) GABA immunoreactivity was expressed very early (E4), whereas immunoreactivity for glycine appeared relatively late (E8) in embryonic development. (ii) In the ventral horn, GABA immunoreactivity declined, whereas immunoreactivity for glycine gradually increased from E8 onward in such a manner that the sum of glycinergic and GABAergic perikarya remained constant during the second half of embryonic development. (iii) Glycinergic and GABAergic neurons showed different distribution patterns in the spinal gray matter throughout the entire course of embryogenesis as well as in the posthatched animal. When investigating the colocalization of glycine and GABA immunoreactivities, perikarya immunostained for both amino acids were revealed at all developmental stages from E8 onward, and the proportions of glycine- and GABA-immunoreactive neurons that were also immunostained for the other amino acid were remarkably constant during development. The characteristic features of the development of the investigated putative inhibitory spinal interneurons are discussed and correlated with previous neuroanatomical and physiological studies.
利用包埋后免疫细胞化学方法，对胚胎期和孵化后雏鸡腰骶脊髓中假定的抑制性氨基酸神经递质甘氨酸的免疫反应性发育进行了研究。甘氨酸免疫反应性核周体在胚胎第8天（E8）首次在背侧和腹侧灰质中被观察到。免疫染色神经元的数量在E10时急剧增加，并在随后的发育阶段进一步逐渐增加。成熟动物特有的甘氨酸免疫反应性总体模式在E12时已经形成，此后仅略有改变。大多数免疫染色神经元位于假定的背侧深层角（IV - VI层）和VII层，尽管甘氨酸免疫反应性神经元散布在脊髓灰质的整个范围内。通过使用我们之前获得并发表的一些关于胚胎期雏鸡腰骶脊髓中γ-氨基丁酸（GABA）能神经元发育的数据，我们比较了不同发育阶段甘氨酸和GABA免疫反应性脊髓神经元的数量、大小和分布，发现这两类假定的抑制性中间神经元在发育特征上有以下显著差异。（i）GABA免疫反应性在胚胎发育早期（E4）就表达，而甘氨酸免疫反应性出现相对较晚（E8）。（ii）在腹侧角，GABA免疫反应性下降，而甘氨酸免疫反应性从E8开始逐渐增加，使得甘氨酸能和GABA能核周体的总数在胚胎发育后半期保持恒定。（iii）在整个胚胎发生过程以及孵化后动物中，甘氨酸能和GABA能神经元在脊髓灰质中表现出不同的分布模式。在研究甘氨酸和GABA免疫反应性的共定位时，从E8开始的所有发育阶段都发现了对两种氨基酸都进行免疫染色的核周体，并且在发育过程中对另一种氨基酸也进行免疫染色的甘氨酸和GABA免疫反应性神经元的比例非常恒定。对所研究的假定抑制性脊髓中间神经元的发育特征进行了讨论，并与先前的神经解剖学和生理学研究相关联。
