Fine structure of the cardiac muscle cells in the orb-web spider Nephila clavata

Q3 Immunology and Microbiology
Yan Sun, Hyo-Jeong Kim, Myung-Jin Moon
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引用次数: 2

Abstract

The fine structural characteristics of cardiac muscle cells and its myofibril organization in the orb web spider N. clavata were examined by transmission electron microscopy. Although myofibril striations are not remarkable as those of skeletal muscles, muscle fibers contain multiple myofibrils, abundant mitochondria, extensive sarcoplasmic reticulum and transverse tubules (T-tubules). Myofibrils are divided into distinct sarcomeres defined by Z-lines with average length of 2.0?μm, but the distinction between the A-band and the I-bands is not clear due to uniform striations over the length of the sarcomeres. Dyadic junction which consisted of a single T-tubule paired with a terminal cisterna of the sarcoplasmic reticulum is found mainly at the A-I level of sarcomere. Each cell is arranged to form multiple connections with neighboring cells through the intercalated discs. These specialized junctions include three types of intercellular junctions: gap junctions, fascia adherens and desmosomes for heart function. Our transmission electron microscopy (TEM) observations clearly show that spider’s cardiac muscle contraction is controlled by neurogenic rather than myogenic mechanism since each cardiac muscle fiber is innervated by a branch of motor neuron through neuromuscular junctions.

Abstract Image

圆网蜘蛛心肌细胞的精细结构
用透射电镜观察了球蛛心肌细胞的精细结构特征及其肌原纤维组织。虽然肌原纤维条纹不像骨骼肌那样明显,但肌纤维中含有多种肌原纤维、丰富的线粒体、广泛的肌浆网和横小管(t小管)。肌原纤维分为不同的肌节,用平均长度为2.0?μm,但由于在肌节长度上有均匀的条纹,因此a带和i带的区别不明显。由单个t小管与肌浆网末端池配对组成的二元连接主要存在于肌节的a - i水平。每个细胞通过嵌入的圆盘与相邻细胞形成多重连接。这些特化连接包括三种类型的细胞间连接:间隙连接、筋膜粘附和心脏功能的桥粒。我们的透射电镜(TEM)观察清楚地表明,蜘蛛的心肌收缩是由神经源性机制而不是肌源性机制控制的,因为每条心肌纤维都是由运动神经元分支通过神经肌肉连接处支配的。
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来源期刊
Applied Microscopy
Applied Microscopy Immunology and Microbiology-Applied Microbiology and Biotechnology
CiteScore
3.40
自引率
0.00%
发文量
10
审稿时长
10 weeks
期刊介绍: Applied Microscopy is a peer-reviewed journal sponsored by the Korean Society of Microscopy. The journal covers all the interdisciplinary fields of technological developments in new microscopy methods and instrumentation and their applications to biological or materials science for determining structure and chemistry. ISSN: 22875123, 22874445.
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