Comparative Ultrastructure of Cell Membrane Specializations in Vertebrate Cardiac Muscles

DOI Web Site Web Site

Bibliographic Information

Other Title
  • 脊椎動物心筋膜系構造の比較研究
  • セキツイ ドウブツ シンキン マクケイ コウゾウ ノ ヒカク ケンキュウ エイ

Search this article

Abstract

The ultrastructure of ventricular cardiac muscles from representatives of all the vertebrate phyla is examined with the electron microscope using thin sections and freeze-fracture replicas. Contrary to the mammalian heart in which the width of the muscle fiber is usually over 10μm, and T-tubules and sarcoplasmic reticulum (SR) are well developed, non-mammalian cardiac muscles in general show small fiber diameter of less than 5μm, lack T-tubules, and reveal a wide variety in the degree of SR development. The rainbow trout and the lamprey, as well as the sparrow, reveal well-developed SR and numerous subsurface cisternae (SC) in proximity to Z line level. On the other hand, lizard and frog ventricles show poor development of SR and infrequent SC at A band level.<br>Nexus (gap junction) can be identified in all the vertebrate hearts examined by freeze-fracture technique. However, it is much smaller and more sparsely distributed in non-mammalian hearts than in mammals.<br>These morphological differences may imply different electrophysiological properties correlated with the small fiber diameter of the lower vertebrate cardiac muscles.

Journal

Keywords

Details 詳細情報について

Report a problem

Back to top