[Peculiarities of the development of skeletal muscles in physiologically mature and immature mammals].

In one set of experiments, studies have been made on the time during which the membrane potential, action potential, total protein and the content of the dry substance of skeletal muscles of rats and dogs attain the values typical for adult animals. Chronologically, this time is 5-fold shorter in rats, than in dogs. In the other set of experiments, the same indices were studied in physiologically mature (with respect to calendar age) and immature rats and dogs. It was shown that in immature animals these indices are significantly lower than in mature ones. During natural development, physiologically immature organisms are the main objects of elimination at early postnatal stages via natural selection.