Mouse sciatic nerve regeneration through semipermeable tubes: A quantitative model

Abstract

The regeneration of transected mouse sciatic nerves using semipermeable acrylic copolymer tubes to enclose both stumps has been qualitatively assessed from 1 to 30 weeks post-operative. Quantitative morphometric analysis of electron micrograph montages of complete transverse sections of the segment regenerated between stumps has permitted determinations of the percents of total area occupied by the various tissue constituents--blood vessels, epineurium, perineurium, endoneurium, myelinated axon/Schwann cell units, and unmyelinated axon/Schwann cell units. Significant differences were found in the total cross-sectional area of segments regenerated through tubes of 1.0 mm versus 0.5 mm internal diameters. Segments regenerated with the distal stump inserted in the tube contained significantly greater percentages of neural units and were significantly larger at 8 weeks post-operative compared to segments regenerated for 9-10 weeks with the distal stump avulsed. The morphometric method permits rapid quantitation of sizeable electron micrograph montages which at 1300 X permit all types of tissue components, including the unmyelinated axons, to be visualized.

Peripheral Nerve Regeneration in Quail-Chick Spinal Cord Chimeras Treated with Oral Ciclosporin

“…The composition of the re generated connectives was similar to that ob served in mice [21], chicks and quail: a vas cularized connective tissue matrix with lon gitudinally coursing myelinated and unmyeli nated axons arranged in bundles encircled by perineurial cells, and around the perineu rium of larger or multiple bundles, by epineurial layers of collagen and fibroblasts. Except in the refasciculated small bundles in prox imal stump neuromas where fibers are less compact, Schwann cells exhibited character istic flattened profiles, nucleolar material was often compressed or fragmented and the Feulgen-positive nucleolar heterochromatin although observed was less distinct than in the spinal cord and ganglion cells.…”

“…Regeneration of quail-chick chimeric ulnar and median nerves was accomplished in the same manner as in chicks, quail, and ro dents [21]. That quail Schwann cells and neurites participated in the process was con firmed by demonstration of the typical large quail nucleoli both in Schwann cells of regen erated PNS and in a majority of cell nuclei in the 3 most cephalad of the 4 graft-derived spi nal cord segments that form the brachial plexus.…”

“…Regeneration in such chimeric nerves follows the same temporal and anatomic sequence and patterns as in mouse [21] quail and chick. Rejection of the graftderived CNS and PNS tissues had either an acute or chronic course in two chimeras treated with oral ciclosporin.…”

Efecto de la permeabilidad en la regeneración del nervio ciático entubado de rata

“…Esta estructura es similar a otras ya descritas en la literatura utilizando este sistema experimental (6,8,9). La matriz presenta un aspecto difuso y contiene esencialmente células sanguíneas y fibrina.…”

“…El modelo de la entubación se ha convertido en una herramienta experimental muy útil para el estudio de los fenómenos básicos subyacentes en la regeneración del nervio periférico (1-3). Las guías tubulares que se han utilizado son hechas de diversos materiales y permeabilidades: sintéticas impermeables, semipermeables o totalmente permeables; biodegradables o de origen biológico (4)(5)(6)(7)(8)(9). En la rata, los tubos de silicona impermeable permiten la regeneración de un mayor número de fibras mielinicas que los tubos acrilicos semipermeables (10).…”