New adipocyte formation in mice during refeeding after long-term deprivation.

Cell kinetic characteristics of the epididymal adipose tissue of mice were examined during refeeding after prolonged food deprivation. Mature mice were given a glucose-electrolyte solution for 20-40 days, and subsequent to a body weight loss of 35%, they were given normal mouse food ad libitum. After refeeding, their body weight and adipose tissue weight returned to the levels before the deprivation. We examined the formation of new adipocytes in the epididymal adipose tissue with [3H]thymidine autoradiography. Flash labeling experiments revealed that cell proliferation was most active on the 6th day after refeeding and decreased thereafter until the 13th day when few labeled cells were seen. Cumulative labeling experiments showed that replicated poorly differentiated mesenchymal cells developed into adipocytes by storing fat droplets. New adipocyte formation was observed in adult mice during refeeding after long-term deprivation.