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Morphology of human intracardiac nerves: an electron microscope study

Published online by Cambridge University Press:  23 November 2000

NERINGA PAUZIENE
Affiliation:
Laboratory of Electron Microscopy, Kaunas University of Medicine, Kaunas, Lithuania Laboratory of Neuromorphology, Department of Human Anatomy, Kaunas University of Medicine, Kaunas, Lithuania
DAINIUS H. PAUZA
Affiliation:
Laboratory of Neuromorphology, Department of Human Anatomy, Kaunas University of Medicine, Kaunas, Lithuania
RIMVYDAS STROPUS
Affiliation:
Laboratory of Neuromorphology, Department of Human Anatomy, Kaunas University of Medicine, Kaunas, Lithuania
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Abstract

Since many human heart diseases involve both the intrinsic cardiac neurons and nerves, their detailed normal ultrastructure was examined in material from autopsy cases without cardiac complications obtained no more than 8 h after death. Many intracardiac nerves were covered by epineurium, the thickness of which was related to nerve diameter. The perineurial sheath varied from nerve to nerve and, depending on nerve diameter, contained up to 12 layers of perineurial cells. The sheaths of the intracardiac nerves therefore become progressively attenuated during their course in the heart. The intraneural capillaries of the human heart differ from those in animals in possessing an increased number of endothelial cells. A proportion of the intraneural capillaries were fenestrated. The number of unmyelinated axons within unmyelinated nerve fibres was related to nerve diameter, thin cardiac nerves possessing fewer axons. The most distinctive feature was the presence of stacks of laminated Schwann cell processes unassociated with axons that were more frequent in older subjects. Most unmyelinated and myelinated nerve fibres showed normal ultrastructure, although a number of profiles displayed a variety of different axoplasmic contents. Collectively, the data provide baseline information on the normal structure of intracardiac nerves in healthy humans which may be useful for assessing the degree of nerve damage both in autonomic and sensory neuropathies in the human heart.

Type
Research Article
Copyright
© Anatomical Society of Great Britain and Ireland 2000

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