DE ROBERTIS E
J Biophys Biochem Cytol. 1956 May 25;2(3):319-30. doi: 10.1083/jcb.2.3.319.
The submicroscopic organization of the retinal rods of the rabbit has been studied with high resolution electron microscopy in thin longitudinal and cross-sections. The outer rod segment consists of a stack of flattened sacs or cisternae each of them limited by a thin homogeneous membrane of about 30 A. The membrane of the rod sacs is attached to the surface membrane and is also in continuity with short tubular stalks of about 100 to 150 A which apparently end in relation with the connecting cilium. The bundle of filaments that constitute the connection between the outer and the inner segments is described under the name of connecting cilium. This fibrous component has a structure that is very similar to that of the cilium. It shows 9 pairs of peripheral filaments of about 160 A in diameter, a matrix material, and a surface membrane. Very infrequently two central single filaments are observed. The connecting cilium has a typical basal body in the inner segment; its distal end penetrates the outer segment, where it establishes some structural relation to the rod sacs. The relationships and submicroscopic organization of the connecting cilium were studied in longitudinal and in cross-sections passing at different levels of the rod segments. The inner rod segment shows two distinct regions: a distal and a proximal one. The distal region, corresponding to the ellipsoid of classical histology is mainly composed of longitudinally packed mitochondria. It also contains the basal body of the cilium, vacuoles of the endoplasmic reticulum, dense particles, and intervening matrix with very fine filaments. In the proximal region of the inner segment the mitochondria are lacking and within the matrix it is possible to recognize elements of the Golgi complex, vacuoles of the endoplasmic reticulum, dense particles and numerous neuroprotofibrils of 160 to 200 A in diameter which collect and form a definite bundle at the exit of the rod fiber. The interpretation of the connecting fibers as a portion of a cilium and of the outer segment as a differentiation of the distal part of a primitive cilium are discussed. The importance of the continuity of the surface membranes of the outer segment, connecting cilium, and inner segment is emphasized and its possible physiological role is discussed.
利用高分辨率电子显微镜对兔视网膜视杆细胞的亚微观结构进行了研究，观察了薄的纵向和横向切片。视杆细胞的外段由一堆扁平的囊泡或潴泡组成，每个囊泡由一层约30埃厚的薄均质膜界定。视杆囊泡的膜附着于表面膜，还与约100至150埃长的短管状柄相连，这些短管状柄显然终止于与连接纤毛的连接处。构成外段和内段之间连接的一束细丝被称为连接纤毛。这种纤维成分的结构与纤毛非常相似。它显示有9对直径约160埃的外周细丝、一种基质物质和一层表面膜。很少能观察到两条中央单细丝。连接纤毛在内段有一个典型的基体；其远端穿入外段，在那里它与视杆囊泡建立了一些结构关系。在穿过视杆细胞不同水平的纵向和横向切片中研究了连接纤毛的关系和亚微观结构。视杆细胞的内段有两个不同的区域：一个远端区域和一个近端区域。远端区域对应于经典组织学中的椭球体，主要由纵向排列的线粒体组成。它还包含纤毛的基体、内质网的液泡、致密颗粒以及带有非常细的细丝的中间基质。在内段的近端区域没有线粒体，在基质内可以识别高尔基体复合体的成分、内质网的液泡、致密颗粒以及许多直径为160至200埃的神经原纤维，这些神经原纤维在视杆纤维的出口处聚集并形成一个明确的束。文中讨论了将连接纤维解释为纤毛的一部分以及将外段解释为原始纤毛远端部分的分化。强调了外段、连接纤毛和内段表面膜连续性的重要性，并讨论了其可能的生理作用。
