QUANTITATIVE STUDIES OF MUSCLES TRANSPLANTED BETWEEN NORMAL AND DYSTROPHIC MICE

Abstract

Quantitative studies of muscles transplanted between normal and dystrophic miceAuto‐ and heterotransplants of minced tibialis anterior muscle in normal and dystrophic mice, with and without polydimethyl silicone‐capped (PDS) nerve, were examined at 150 days and the following morphological features quantitated: weights of transplants, total number of fibres, frequency and diameter of Type 1 and 2 fibres, number of fibres with internal nuclei, frequency of fibres undergoing splitting, degeneration and regeneration, and the amount of connective tissue. Similar studies were made on intact 150 day old normal and dystrophic muscles. In the intact animals there was no significant difference between male and female muscles, but dystrophic muscles were smaller and contained more connective tissue and fibres showing internal nuclei, splitting, degeneration and regeneration. The diameter of fibres was larger in male muscle of normal and female muscle of dystrophic mice. All 150 day old transplants in normal mice with PDS‐capped nerve and dystrophic mice consisted entirely of connective tissue. Only transplants in normal mice with intact nerve were viable. Both normal and dystropic transplants were smaller than unoperated normal muscle but their fibres differentiated normally and showed less variation in size than those of intact dystrophic muscle. They also contained some fibres with internal nuclei and fibres undergoing splitting. The data indicate that under the influence of the normal nerve dystrophic transplants fare just as well and are quantitatively similar to normal transplants. It is suggested that the motor nervous system plays an important role in the pathogenesis of murine dystrophy.