Zhang L, Ina K, Kitamura H, Campbell G R, Shimada T
Department of Anatomy, Oita Medical University, Japan.
Arch Histol Cytol. 1996 Dec;59(5):453-65. doi: 10.1679/aohc.59.453.
The intercalated discs of working myocardium and Purkinje fibers of the monkey heart were examined by scanning and transmission electron microscopy. The NaOH/ultrasonication technique resulted in the digestion of connective tissue and a separation of the intercellular junctions of intercalated discs, such that these could be visualized three-dimensionally. The intercalated discs of ventricular myocytes, atrial myocytes and Purkinje fibers vary considerably in number and configuration, as do the intercalated discs of the three different layers of the ventricular myocardium. Myocytes in the subepicardial, middle and subendocardial layers of the ventricle have 1-3, 4-5 and 5-6 intercalated discs at the end of these cells, respectively. Those in the endocardial layer are characterized by the presence of small laterally-placed intercalated discs. Atrial myocytes and Purkinje fibers usually only have 1-2 intercalated discs. Individual intercalated discs in ventricular myocytes have complicated stairs with 10-30 steps and corresponding risers, while those of atrial myocytes and Purkinje fibers have simple stairs with 1-3 steps and risers. Steps equivalent to the plicate segments are characterized by densely-packed microplicae and finger-like microprojections which greatly increase surface area in ventricular myocytes. Microprojections in atrial myocytes and Purkinje fibers are sparse by comparison. Risers equivalent to the interplicate segments containing large gap junctional areas are most numerous in left ventricular myocytes, followed by right ventricular myocytes, Purkinje fibers and atrial myocytes in decreasing order. The geometric arrangement of the various types of myocytes may be related with impulse propagation. Large intercalated discs of cell trunks and series branches may participate in longitudinal propagation, while small laterally-placed ones may be the site of transverse propagation.
采用扫描电子显微镜和透射电子显微镜对猴心脏工作心肌和浦肯野纤维的闰盘进行了检查。氢氧化钠/超声处理技术可消化结缔组织并分离闰盘的细胞间连接，从而能够对其进行三维可视化观察。心室肌细胞、心房肌细胞和浦肯野纤维的闰盘在数量和形态上有很大差异，心室肌三层不同层面的闰盘也是如此。心室心外膜下层、中层和心内膜下层的肌细胞在细胞末端分别有1 - 3个、4 - 5个和5 - 6个闰盘。心内膜层的肌细胞以侧面有小的闰盘为特征。心房肌细胞和浦肯野纤维通常只有1 - 2个闰盘。心室肌细胞中的单个闰盘有复杂的阶梯结构，有10 - 30级台阶和相应的梯级，而心房肌细胞和浦肯野纤维的闰盘有简单的阶梯结构，有1 - 3级台阶和梯级。与褶皱段相当的台阶以密集排列的微褶皱和指状微突起为特征，这大大增加了心室肌细胞的表面积。相比之下，心房肌细胞和浦肯野纤维中的微突起较少。与含有大间隙连接区域的褶皱间段相当的梯级在左心室肌细胞中最多，其次是右心室肌细胞、浦肯野纤维和心房肌细胞，数量依次减少。各种类型肌细胞的几何排列可能与冲动传播有关。细胞主干和串联分支的大闰盘可能参与纵向传播，而侧面小的闰盘可能是横向传播的部位。
