Muscle autografts in nerve gaps. Pattern of regeneration and myelination in various lengths of graft: an experimental study in guinea pigs

Abstract

Denatured muscle autograft contains large inner basement membrane tubes, which are anatomically and chemically similar to peripheral nerve basement membrane tubes. These autografts can be used for bridging nerve gaps. In 30 Duncan-Hartley guinea pig sciatic nerves, experimentally induced gaps of 5mm, 10mm, and 15mm were bridged with freeze-thawed gluteus maximus muscle autografts. The results were studied for up to 12 weeks. Functional and histological criteria, morphometry, and electron microscopy were used for the evaluation of regeneration and myelination. Functional recovery was seen by 12 weeks in 5-mm grafts. Morphometric study of 1-pm semi thin sections was carried out, and the number of axons in each representative field was studied, as the percentage of myelinated and unmyelinated fibers; the thickness of myelin was also measured. The percentage of myelinated and unmyelinated fibers was estimated by transmission electron microscopy (TEM). Axonal repopulation in the distal segment was seen by the third week in the 5-mm graft, and myelination was more extensive in this group in comparison to the others. On morphometric analysis, the mean fiber diameter in the distal part of the graft was 3.81pm in the 5-mm graft and 2.9pm in the 15-mm graft at 12 weeks. The results of this experiment prove that the length of the graft is an important consideration for muscle autografts when they are used for mixed peripheral nerve repair.