Transmission electron microscopical analysis of sheep cardiac nerves

Abstract

The aim of the study was to determine the ultrastructural particularities of the intrinsic cardiac nerves of popular experimental animal - sheep. Contrary to the well investigated small laboratory animals, however, little is known about the organization of neural structures distributed within the walls of the heart of sheep. Materials and methods. In this study 319 tissue samples from 2 adult sheep were analysed with transmission electron microscope. The characteristics of axons, nerve fibres and nerves were evaluated. Results. Observations using the electron microscope indicate that epicardial nerves had oblong shape which was influenced by the location of the nerve. Characteristic features of sheep intracardial nerves: (a) nerve fibres distributed very close each other and embedded in dense endoneurium; (b) myelinated fibres were found seldom and unmyelinated nerve fibres dominated; (c) unmyelinated nerve fibres were composed from single axons mainly; (d) axons were very thin; (e) Schwann cells enclosed axons by very thin rims; (f) majority of axons were not fully covered by Schwann cells and were in direct contact with basal lamina; (g) majority of axons were individually covered by Schwann cell. [...].