Capillary Distribution and Fiber Characteristics in Skeletal Muscle of Stress‐Susceptible Animals

Abstract

SUMMARY Muscle from stress‐susceptible and stress‐resistant pigs was studied for capillary distribution and fiber characteristics. More capillaries were associated with red fibers than white fibers and there was a greater capillary to fiber ratio in red than white muscle. There was no difference in capillary fiber ratio between normal (from stress‐resistant pigs) and PSE (from stress‐susceptible pigs) muscle. Muscle from stress‐susceptible animals had more intermediate fibers than did muscle from stress‐resistant animals. Certain intermediate fibers from stress‐susceptible animals had a high amylophosphorylase and ATPase activity. It was postulated that such fibers are important in the drastic post‐mortem muscle behavior in stress‐susceptible animals and may represent the characteristic which causes muscle to become PSE.