Criswell M H, Brandon C
Department of Cell Biology and Anatomy, University of Health Sciences, Chicago Medical School, IL 60064-3095.
Brain Res. 1992 Apr 10;577(1):101-11. doi: 10.1016/0006-8993(92)90542-h.
Turtle retinas were processed immunocytochemically and histochemically to detect the presence of choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and glutamate decarboxylase (GAD). We observed cholinergic and gamma-aminobutyric acid (GABA)ergic neurons in the proximal retina, as expected, and in the distal retina as well. ChAT immunoreactivity in the distal retina was observed within the axons and pedicles of numerous cone photoreceptors, suggesting that a population of turtle cone photoreceptors uses ACh as a neurotransmitter. Type L2 horizontal cells were immunoreactive for GAD, and their dendrites invaginated into cone pedicles. AChE histochemistry revealed processes within the outer plexiform layer which formed a loosely organized lattice. In the proximal retina, labeling for ChAT and GAD was similar to that reported by previous investigators. Processes from ChAT-labeled amacrine cells in the inner nuclear layer formed a stratum within the distal inner plexiform layer (IPL) (at 16-21% relative IPL depth), and processes from ChAT-labeled amacrines in the ganglion cell layer formed a proximal ChAT stratum (at 55-58% relative IPL depth). In addition, six AChE-labeled bands and five GAD-labeled bands were observed within the IPL of stained retinas. Therefore, we determined that the two broadest AChE-labeled bands and the two broadest GAD-labeled bands overlapped the two labeled ChAT strata. The evidence for cholinergic and GABAergic processes in both the inner plexiform layer and the outer plexiform layer, combined with electrophysiological evidence from other investigators, raises the possibility that distal retinal neurons may be involved in the encoding of directional information.
对龟视网膜进行免疫细胞化学和组织化学处理，以检测胆碱乙酰转移酶（ChAT）、乙酰胆碱酯酶（AChE）和谷氨酸脱羧酶（GAD）的存在。正如预期的那样，我们在视网膜近端观察到了胆碱能和γ-氨基丁酸（GABA）能神经元，在视网膜远端也观察到了。在许多视锥光感受器的轴突和视锥小足内观察到视网膜远端的ChAT免疫反应性，这表明一群龟视锥光感受器使用乙酰胆碱作为神经递质。L2型水平细胞对GAD呈免疫反应，其树突内陷到视锥小足中。AChE组织化学显示外网状层内的突起形成了一个松散组织的晶格。在视网膜近端，ChAT和GAD的标记与先前研究者报道的相似。内核层中ChAT标记的无长突细胞的突起在远端内网状层（IPL）内形成一层（相对IPL深度为16 - 21%），神经节细胞层中ChAT标记的无长突细胞的突起形成近端ChAT层（相对IPL深度为55 - 58%）。此外，在染色视网膜的IPL内观察到六条AChE标记带和五条GAD标记带。因此，我们确定两条最宽的AChE标记带和两条最宽的GAD标记带与两条标记的ChAT层重叠。在内网状层和外网状层中胆碱能和GABA能突起的证据，结合其他研究者的电生理证据，增加了视网膜远端神经元可能参与方向信息编码的可能性。
