Bhatnagar K P, Spoonamore B A
Acta Anat (Basel). 1979;105(2):157-80.
This investigation describes the ultrastructure of the atrioventricular node of Eptesicus fuscus. Two conducting cells types (nodal and transitional) are indentified which differ in location, myofibrillar content, and types of intercellular junctions. Centrally located nodal cells display variable staining intensity and contain disorganized myofibrils which rarely form sarcomeres. Desmosomes and nexus-like junctions connect the nodal cells. Transitional cells, situated peripherally, exhibit distinct sarcomeres and are attached to the adjacent cells through desmosomes and underdeveloped intercalated discs. Longitudinal arrangement of the mitochondrial cristae is frequently seen in both cells types. In the connective tissue stroma, numerous capillaries (with micropinocytotic vesicles), axons, and possibly axonal terminals, some filled with vesicles, are observed. A large ganglionated nerve trunk is present on the nodal periphery. True nexuses and neuromuscular junctions are not observed. It is suggested that nodal cell types previously reported in different vertebrates under various names are merely simple variations of the two basic types of conducting cell--nodal and transitional. No interspecific differences are observed between these cells of the big brown bat compared with those in other vertebrates.
本研究描述了棕蝠房室结的超微结构。识别出两种传导细胞类型（结细胞和移行细胞），它们在位置、肌原纤维含量和细胞间连接类型上存在差异。位于中央的结细胞染色强度可变，含有排列紊乱的肌原纤维，很少形成肌节。桥粒和类似连接子的连接将结细胞连接起来。位于周边的移行细胞表现出明显的肌节，通过桥粒和发育不全的闰盘与相邻细胞相连。在这两种细胞类型中都经常能看到线粒体嵴的纵向排列。在结缔组织基质中，观察到许多毛细血管（带有微饮小泡）、轴突以及可能的轴突终末，有些轴突终末充满了小泡。在结的周边有一条粗大的有神经节的神经干。未观察到真正的连接子和神经肌肉接头。有人提出，先前在不同脊椎动物中以各种名称报道的结细胞类型仅仅是两种基本传导细胞类型——结细胞和移行细胞的简单变体。与其他脊椎动物相比，大棕蝠的这些细胞之间未观察到种间差异。
