Microvascular pattern during the growth of regenerating muscle fibers in the rat.

Quantitative methods were used to analyze changes in the capillarization of skeletal muscle during regeneration. The H-E staining technique was used to establish three arbitrary stages of fiber regeneration on the basis of qualitative histological evaluation. ATPase and light microscopic techniques were used to calculate capillary density, the number of capillaries surrounding each fiber, and the fiber area served by each capillary, for each of the three stages established. The results obtained indicated variations in the vascularization of regenerating fibers from one stage of maturity of another: capillarization was greater in the initial stages of regeneration, returning gradually to normal values by the final stages of the process. Interestingly enough the pattern in the capillarization of skeletal muscle during regeneration seems to be similar to that taking place during postnatal muscle development. Both processes appear to be governed by the increase in fiber size.