Summary
The capillaries in the atrioventricular node and atrioventricular bundle of the heart (mammals) were investigated by thin sections and freezeetch replicas. Fenestrated endothelial cells were found to occur in all mammals examined in this study. These fenestrations (500±50 Å diameter) are bridged by a diaphragm and occur in relatively small sieve areas. In contrast to the AV-node and AV-bundle, the non-specialized myocardium is supplied by continuous capillaries. The presence of the fenestrated capillary in the conduction system of the heart may serve to increase both permeability and passive transport capacity.
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The studies were supported by the German Research Foundation within the SFB 90 “Cardiovasculäres System”
We are indebted to Prof. H.D. Fahimi and Prof. W.G. Forssmann, Departments of Anatomy, University of Heidelberg, for many helpful discussions and to Dr. Paula Antony and Mr. Steven Meairs for reviewing the manuscript. The technical assistance of Ms. Christiane Müller and Ms. Ursula Graber and the secretarial help of Mrs. Roswitha Botz and Ms. Annemarie Achten is gratefully acknowledged
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Weihe, E., Kalmbach, P. Ultrastructure of capillaries in the conduction system of the heart in various mammals. Cell Tissue Res. 192, 77–87 (1978). https://doi.org/10.1007/BF00231024
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DOI: https://doi.org/10.1007/BF00231024