Intrinsic microvasculature of the sciatic nerve in the rat

Abstract

Microvasculature associated with the sciatic nerve was examined using high-resolution micro-CT scanning in one group of rats and surgical exploration in another. The results indicate that blood supply to the sciatic nerve is an "open-ended" system in which the vessels run longitudinally within the epineurium and connect with external vasculature primarily at junction points. Although the range of vasculature found extended down to 4-5 μ, only a few isolated vessels of this size were found, with no capillary "mesh" as such, possibly because of the close proximity of the intrinsic vessel to nerve fibers within the epineurium. While the study did not include direct measurements of flow or nerve function, the "open-ended" pattern of vasculature found has important implications regarding the relationship between the two. Specifically, the nerve is less vulnerable to a severe or complete disruption in blood supply than it would be under a close-ended system such as that of the heart or brain, where a severe disruption can occur with the obstruction of only a single vessel. Indeed, the pattern of vasculature found, subject to further study of vasculature at the capillary level, suggests that flow within the intrinsic vessels may be in either direction, depending on circumstances, somewhat like flow within the circle of Willis in the cerebral circulation.

Variations of the sciatic nerve anatomy and blood supply in the gluteal region: a review of the literature

“…Zamir et al . used high‐resolution micro‐computerized tomography scanning and surgical dissection to study the microvascular supply of the sciatic nerve in rats . Their results confirmed those of Lundborg, describing an ‘open‐ended’ system in which longitudinal epineurial vessels connect with the external or extrinsic blood supply at certain points.…”

Exercise training enhances insulin-stimulated nerve arterial vasodilation in rats with insulin-treated experimental diabetes

“…Thus, because Doppler ultrasound is limited to a single epineurial vessel, it may not capture reductions in endoneurial-specific flow. However, the sciatic nerve contains feed arteries originating from multiple locations that do not necessarily branch into a capillary plexus and has been described as an anastomotic vascular network that may contain bidirectional flow (3,9,70). Such a pattern of tissue perfusion limits the interpretation of gross flow measurements and highlights the benefit of quantifying exclusive arterial inflow responses.…”

Erbium-Based Perfusion Contrast Agent for Small-Animal Microvessel Imaging

“…Preclinical exogenous agents, of larger molecular sizes (i.e., >1100 Da), can remain within the blood pool for hours [ 13 , 14 ]. These contrast agents are typically iodine-, barium-, or lead-based and have been used effectively to study vessel microarchitecture in the heart [ 15 , 16 ], kidney [ 17 , 18 ], tumours [ 19 , 20 ], nerves [ 21 – 23 ], and long bones [ 24 , 25 ]. However, these preclinical contrast agents do not exhibit optimal X-ray absorption (and hence do not optimize SNR) on a large installed base of micro-CT machines that typically operate at a maximum of 90 kilo-electron volts (keV).…”