Abstract: Anterior pagoda (AP) neurons of leeches were marked by intracellular injection of horseradish peroxidase (HRP). The intercellular connection were observed under transmission electron microscope between the smooth muscle cells in outer capsule and inner capsule of the neural ganglion, and between the marked axonal terminals of AP neuron and smooth muscle cells. Usually, single smooth muscle cell spread over the outer and inner capsules of ganglia in the shape of spindle-and elliptical-like respectively. There are two kinds of filaments:thin and thick filaments and dense patches in the smooth muscle cells. The membrane of smooth muscle cells grew out protrusions. Many glycogen granules, mitochondria and rough endoplasmic reticulum can be seen in the cytoplasm of smooth muscle cells. The distance between embedded smooth muscle cells in outer capsule ranges from 13.1 to 26.1 nm. This paper is the first report on the synapses formed between axonal processes and smooth muscle cells in the outer capsule of leech ganglion, for the chemical synapse the intercellular cleft is measured in 10.2 to 15.3nm; as for the width of intercellular gap between the marked AP axonal terminal and smooth muscle cell of the outer capsule ranges from 2 to 2.5nm that corresponded to the width of gap junction.

Key words: smooth muscle cell, chemical synapse, gap junction, Whitmania pigra, AP neuron, opposite membrane structure

摘要： 用胞内注射辣根过氧化物酶(HRP)的方法标记中华宽体金线蛭AP神经元。透射电镜下观察到神经节的内、外囊中的平滑肌细胞膜间、以及标记AP神经元的轴突末梢膜与神经节中平滑肌细胞间的连接。通常，单个的平滑肌细胞散布在神经节的内、外囊中，分别为椭圆形和梭形。平滑肌细胞含粗、细两种肌丝，有密斑，具有许多突起。神经节外囊中平滑肌细胞的细胞质中央区有许多糖元颗粒和一些线粒体及粗面内质网；两个嵌合的平滑肌细胞膜间距为13.1～26.1nm。首次观察到神经元的轴突末梢与外囊内的平滑肌细胞形成化学突触，突触裂隙10.2～15.3nm；AP标记末梢膜与外囊平滑肌细胞膜之间的间距为2.0～2.5nm，相当于缝隙连接的并置膜结构。

关键词: 平滑肌细胞, 化学突触, 缝隙连接, 并置膜结构, 中华宽体金线蛭, AP神经元