Microscopic anatomy of brachial plexus branches in Wistar rats

Abstract

In the present study, we analyze the morphology and morphometry of the lateral proper digital nerve of the third finger, and of the proximal and distal segments of the ulnar, median, and radial nerves, in Wistar rats 4 or 7 weeks old. The fascicular area and diameter were generally significantly greater in the proximal compared to distal segments and tended to be larger in 7-week-old compared to 4-week-old rats (e.g., median nerve area of 0.13 mm 2 for the proximal and 0.07 mm 2 for distal segments in 4-weekold rats, and 0.17 and 0.10 mm 2 , respectively, for the proximal and distal segments of 7-week-old rats). The number of fascicles was significantly greater while the number of myelinated fibers was significantly less in the distal segments (e.g., 1,359 and 509 myelinated fibers, respectively, in the proximal and distal segments of the radial nerve 4-week-old rats). There was no significant difference in these parameters between the two age groups. The diameter of the myelinated fibers and their respective axons increased from 4 to 7 weeks of age (e.g., myelinated fiber diameter of 4.10 mm in 4-week-old animals and 4.7 mm in the ulnar nerve proximal segment of 7-week-old rats). The g-ratio regression line (axon diameter vs. fiber diameter quotient) was outlined for all the nerves studied here. Differences in myelinated fiber density were detected between the segments of the radial nerve, accompanying the number of myelinated fibers. Detailed knowledge of the microscopic anatomy of rat forelimb nerves provides control data for comparison with studies of experimentally induced neuropathies, which can shed more light on human neuropathies. Anat Rec, 290:477-485, 2007. 2007 Wiley-Liss, Inc.

Aspects of the Macro and Microscopic Anatomy of the Sciatic Nerve in Wistar Rats

“…The absence of significant branching of the sciatic nerve (Schmalbruch) associated with a constant number of nerve fibers during development (Jeronimo et al) explains our findings. Also, the absence of significant difference in the number of fibers between proximal and distal segments in animals of the same age has been documented for the sciatic and other nerves (Dyck et al, 1984;Jeronimo et al;Santos et al). The numbers presented in this section are similar to those reported for Wistar rats (Schmalbruch; Yagihashi et al; Voinesco et al; Prodanov & Feirabend); and for Lewis and Sprague-Dawley rats (Dyck et al;Mackinnon et al, 1991).…”

“…They were then prepared, cut, stained, and observed as described previously (Santos et al, 2007). The nerves were kept in the fixative solution for an additional 48 h and processed for epoxy resin embedding (Poly/Bed 812; Polysciences, Warrington, PA).…”

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

“…The nerve was cut into 0.5 μm thick sections using a microtome (MT 6000XL-RMC), stained with toluidine blue, and mounted using Entellan ® for light microscopy analysis. Details of the methods used have been published in previous studies 6,20,21 .…”

The rabbit brachial plexus as an experimental model – anatomy and surgical approach

“…The brachial plexus of rat is formed by contribution of ventral rami of C5, C6, C7, C8, T1 and T2 spinal nerves (Santos et al 2007). On the other hand, in literature it is reported that ramus ventralis of T2 spinal nerve in rats is not involved (Bertelli et al 1992).…”