A histomorphometric study of unmyelinated fibers of the fibular nerve in Wistar rats

Abstract

There are few histomorphometric studies on the unmyelinated fibers of the fibular nerve in rats, and the number of experimental studies using this nerve has been increasing in the last years. Sixty-two percent of the endoneurial area from 10 fibular nerves of adult Wistar rats was scanned by electron microscopy, and digitized. The total number of unmyelinated axons (1.882 ± 271) was significantly lesser, and their axon diameters (0.2 µm to 2.8 µm) significantly higher than that determined in previous studies. The histogram peaked at 1 µm. The differences could be due to the nerve sampled area, the number and the age of the animals evaluated, and the laboratory techniques used. This study brings new and referential data to be used in experimental investigations involving histomorphometric evaluation of the rat fibular nerve.

Plasticity of Unmyelinated Fibers in a Side-to-end Tubulization Model

“…All images were analyzed. Owing to variability in the fascicular area, 2 we obtained a mean of 413 images per nerve.…”

“…Measurements of the internal fascicular area (mm2) were similar to those obtained in semithin sections; since semithin sections produced clearer images, we used them to measure the fascicular areas. 2…”

“…There are few morphological and morphometric studies of unmyelinated nerve fibers, despite their being widely distributed and processing important sensory and autonomic information. 1,2 Unmyelinated fibers are significant components of both the autonomic nervous system and sensory afferents, transmitting information from cutaneous and visceral areas to the central nervous system, and are primarily responsible for tactile, thermal, and pain sensations. 3–7 Regeneration of unmyelinated fibers leading to reinnervation is important because those sensation modalities are crucial for skin preservation, preventing contact pressure ulcers (bedsores) formation in man, 8–11 and also autophagy or autotomy in rats.…”

“…Previous studies quantifying unmyelinated fibers of the fibular nerve have yielded conflicting results concerning axonal number. 2 Research published by Kovacic et al 38–42 demonstrated growth of sural nerve unmyelinated fibers to the injured fibular nerve using SEN.…”