Peterson E H, Ulinski P S
J Comp Neurol. 1979 Jul 1;186(1):17-42. doi: 10.1002/cne.901860103.
Multiple pathways for the transmission of visual information from retina to brain have been described in reptiles, but little is known about their functional organization. These parallel channels begin at the retina, and we have therefore begun to study the functional organization of retinal ganglion cells in the turtle, Pseudemys scripta elegans. This paper describes the numbers and distribution of cells in the ganglion cell layer. To develop criteria for the identification of ganglion cells, we labelled them retrogradely by applying horseradish peroxidase (HRP) to the optic nerve. Ganglion cells were found to vary substantially in size and cytology. In low density areas of the retina, ganglion cells typically have cytoplasm with well developed Nissl substance, a distinct, pale nucleus, and a large nucleolus. In high density areas of retina, ganglion cells are small, densely staining, and gliaform. The average minimum proportion of ganglion cells in the ganglion cell layer is 75--80% of total profiles. No more than five or six percent of profiles in the ganglion cell layer are neurons which do not send an axon into the optic nerve (displaced amacrine cells or intraretinal association cells). The ganglion cell layer of P. s. elegans can be divided into a number of regions on the basis of cell density. Isodensity maps constructed from Nissl-stained, wholemounted retinas indicate that there is an elongated region of high ganglion cell density, the visual streak, which extends from nasal to temporal retina and is oriented such that its long axis follows the horizontal axis of the eye. The streak is aligned with the externally visible iris line. Seen in cross-section, the ganglion cell layer in the streak is three to four cells thick; in nonstreak retina, ganglion cells form only a monolayer of somas. Ganglion cell density drops off more rapidly above the streak than below it. The temporal arm of the streak is both shorter and broader than the nasal arm. There is a peak in ganglion cell density at the midpoint of the streak, in the approximate center of the retina. Here, ganglion cell densities exceed 20,000 cells mm-2. The total number of ganglion cells in the retina is 350,000--390,000.
在爬行动物中，已经描述了从视网膜到大脑的多种视觉信息传递途径，但对它们的功能组织却知之甚少。这些平行通道始于视网膜，因此我们开始研究锦龟（Pseudemys scripta elegans）视网膜神经节细胞的功能组织。本文描述了神经节细胞层中细胞的数量和分布。为了制定识别神经节细胞的标准，我们通过将辣根过氧化物酶（HRP）应用于视神经来逆行标记它们。发现神经节细胞在大小和细胞学上有很大差异。在视网膜的低密度区域，神经节细胞通常具有含有发育良好的尼氏体的细胞质、一个清晰、浅色的细胞核和一个大核仁。在视网膜的高密度区域，神经节细胞小、染色深且呈神经胶质样。神经节细胞层中神经节细胞的平均最小比例为总轮廓的75% - 80%。神经节细胞层中不超过5%或6%的轮廓是不向视神经发送轴突的神经元（移位无长突细胞或视网膜内联合细胞）。根据细胞密度，锦龟的神经节细胞层可分为若干区域。从尼氏染色的整个视网膜构建的等密度图表明，有一个神经节细胞高密度的细长区域，即视觉条纹，它从视网膜鼻侧延伸至颞侧，其长轴沿眼睛的水平轴方向排列。该条纹与外部可见的虹膜线对齐。从横截面看，条纹处的神经节细胞层有三到四个细胞厚；在非条纹视网膜中，神经节细胞仅形成单层胞体。条纹上方神经节细胞密度下降比下方更快。条纹的颞侧臂比鼻侧臂更短更宽。在条纹的中点，即视网膜的大致中心，神经节细胞密度有一个峰值。此处，神经节细胞密度超过20,000个细胞/mm²。视网膜中神经节细胞的总数为350,000 - 390,000个。
