Some Aspects of Muscle Regeneration

Abstract

Publisher Summary This chapter discusses some aspects of muscle regeneration. Regeneration of striated muscle must produce, to be complete, a multinucleated fiber attached at both ends containing myofibrils that can contract under a nervous stimulus. This is a minimum requirement for a functional restoration. But muscle tissue, being one of the most specialized in both form and function, is also one for which regenerative processes must occur in a delicately coordinated sequence. Whatever the method of destruction of the muscle (cutting, chemical or physical necrosis, ischemia), regeneration phenomena begin before destruction and phagocytosis of the destroyed parts are completed. In all cases of muscle regeneration, there is an early stage in which free cells are particularly numerous. All types of connective tissue cells are present. Part of the fibroblast like cells are myoblasts in the sense just defined but they cannot readily be recognized in sections with the usual histological techniques. The synthesis of the muscle proteins and the building up of myofibrils occur essentially in the sarcoblast. The sarcoblast includes all polynucleated stages before the muscle fiber is well differentiated. Thus its aspects change with time and may be variable. The chapter also discusses the formation of myohbrils, internal organization of the muscle fiber, the relation of the regenerated musclc fiber to the con nective tissue, and effect of innervation on muscle regeneration. Taking into account both in vivo and in vitro experiments, it seems that differentiation of regenerating muscle occurs in the absence of nerves. But later growth needs some influence from the nervous system.