PROLIFERATION OF SMALL FAT-CELLS DERIVED FROM UNILOCULAR FAT-CELLS OFRATS IN COLLAGEN GEL MATRIX CULTURE

The proliferative ability of fat cells has been studied both in the ad ipose tissue in vivo and in culture. We studied the proliferation of u nilocular fat cells of young rats in a three-dimensional collagen gel matrix culture, which provides a physiological environment for fat cel ls. In this setting, the unilocular fat cells were able to maintain th eir cellular functions and actively proliferate. In this study using c ells derived from 3 to 6-week-old rats, we observed the appearance of very small fat cells at the surface of unilocular fat cells following the division of the nucleus. We concluded that small fat cells were cr eated mostly in a ''budding'' manner, and then proliferated. Insulin a ccelerated both the budding and proliferation process. In other uniloc ular fat cells, lipid droplets divided after the division of the nucle us, and very small fat cells appeared within the unilocular fat cells in a ''sharing'' manner. Adenosine deaminase, a potent lipolytic facto r, accelerated this process. An analysis of the cellular volume by a C oulter counter confirmed the proliferation of small fat cells derived from the unilocular fat cells, These small fat cells grew and develope d into unilocular fat cells. It is supposed that not all unilocular fa t cells are terminally differentiated, nor do they lose their prolifer ative activity.