Ultrastructural investigation of the aortic depressor nerve in Wistar and Wistar‐Kyoto rats

Abstract

Ultrastructural study of the aortic depressor nerve (ADN) [1] showed differences on the morphology and morphometry between normotensive Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR), particularly in the number of unmyelinated fibers. The aim of the present study was to investigate if there are ultrastructural differences on the AND of two different normotensive rats strains. Twelve Wistar rats (WR) and 13 WKY had their left ADN fixed in 2,5% glutaraldehyde. Thin cross sections of proximal and distal segments of the ADN were studied by transmission electron microscopy and a morphometric study of the unmyelinated fibers was performed. Comparison between proximal and distal segments of the two strains revealed a longitudinal symmetry. Comparison between strains revealed that, despite the fact that WR are heavier (body weight = 339 ± 17g for WR and 277 ± 54 for WKY) than WKY, ADN unmyelinated fiber number and size is significantly larger in WKY. Unmyelinated fiber distribution is unimodal in both segments for both strains but WKY distribution was skewed to the right with a high percentage of fibers larger than 1.5 μm. Average values of unmyelinated fibers morphometric parameters are higher in WKY due to a larger number of fibers bigger than 1.5 μm.Grant Funding Source: FAPESP, CNPQ, CAPES and FAEPA