POSTNATAL-DEVELOPMENT OF SHIVERING IN THE MOUSE

1. 1.|The postnatal development of muscle shivering in cold was studied in albino laboratory mice aged from 1 to 20 days using gross electromyography. 2. 2.|Cold-shivering occurred in most animals at the age of 5 days, but the age at which it began showed large inter-individual variation. 3. 3.|A tactile stimulus which evoked an orienting reflex elicited bursts of shivering in cold in animal aged 3-4 days and also in older animals during the intervals they did not shiver. This response habituated rapidly. 4. 4.|Between the ages of 5 and 20 days the body temperature for the onset of shivering increased linearly to the level found in adult mice. This was taken to indicate a change in the threshold temperature of the central control of shivering. The concomitant increase in the muscle size also contributes to the development of the thermoregulatory function of shivering. © 1979.