Hidaka S, Christensen B N, Naka K
J Comp Neurol. 1986 May 8;247(2):181-99. doi: 10.1002/cne.902470205.
Synaptic structures between receptors and horizontal and bipolar cells in the outer plexiform layer (OPL) of Golgi-impregnated catfish retina were examined by conventional electron microscopy of serial ultrathin sections and by high-voltage electron microscopy (HVEM) of thick sections. Cone terminals contained multiple synaptic ribbons and rod terminals contained single synaptic ribbons. This observation was used to identify these two types of photoreceptors. The cone horizontal cell, located in the most distal part of the inner nuclear layer (INL), invaginated only cone terminals, whereas the rod horizontal cell, located in the proximal part of the INL, invaginated only rod terminals. Both lateral elements of the triad in the rod terminal originated from a single rod horizontal cell whereas the same structures in the cone terminal were often derived from several cone horizontal cells. Golgi-impregnated catfish bipolar cells were classified into two types based on the differences in their axonal arborization as described by Famiglietti et al. ('77). Axonal endings of type a bipolar cells were located in the distal part, sublamina a, of the inner plexiform layer (IPL), and axonal endings of type b cells were located in the proximal part, sublamina b, of the IPL. Dendrites from type a bipolar cells made direct contact with the synaptic ribbons in both rod and cone terminals whereas those from type b cells made indirect contact with the ribbons in both rod and cone terminals, but rare direct contact with the ribbon in rod terminals were also seen. In addition, bipolar cells made basal junctions or superficial contacts in both rod and cone terminals. The "lateral" processes of bipolar cells invaginating rods penetrated between the rod terminal and rod horizontal cell processes, and made basal junctions with both rod terminals and rod horizontal cells. There was no definitive morphological feature that could be associated with sign-conserving and sign-inverting signal transmission.
通过对连续超薄切片进行常规电子显微镜检查以及对厚切片进行高压电子显微镜（HVEM）检查，研究了高尔基染色的鲶鱼视网膜外网状层（OPL）中受体与水平细胞和双极细胞之间的突触结构。视锥细胞终末含有多个突触带，视杆细胞终末含有单个突触带。这一观察结果被用于识别这两种类型的光感受器。视锥水平细胞位于内核层（INL）的最远端，仅内陷视锥细胞终末，而视杆水平细胞位于INL的近端，仅内陷视杆细胞终末。视杆细胞终末三联体的两个侧向成分均来自单个视杆水平细胞，而视锥细胞终末的相同结构通常来自多个视锥水平细胞。根据Famiglietti等人（1977年）描述的轴突分支差异，将高尔基染色的鲶鱼双极细胞分为两种类型。a型双极细胞的轴突终末位于内网状层（IPL）的远端a亚层，b型细胞的轴突终末位于IPL的近端b亚层。a型双极细胞的树突与视杆和视锥细胞终末中的突触带直接接触，而b型细胞的树突与视杆和视锥细胞终末中的突触带间接接触，但也可见与视杆细胞终末中的突触带罕见的直接接触。此外，双极细胞在视杆和视锥细胞终末都形成了基底连接或表面接触。内陷视杆细胞的双极细胞的“侧向”突起穿透视杆细胞终末和视杆水平细胞突起之间，并与视杆细胞终末和视杆水平细胞都形成基底连接。没有明确的形态学特征可以与信号保守和信号反转信号传递相关联。
