Longitudinal study of adipose cell size in the dorsoscapular and perirenal depots of the growing rabbit.

The changes in fat cell size during normal growth of New Zealand rabbits were investigated longitudinally with serial dorsoscapular and perirenal fat biopsies. A remarkably complex pattern of changes appeared when individual evolutions were considered. About 50% of the rabbits were characterized by "significant drops" of mean diameter during fat tissue growth with shifting of distributions toward the smaller cells. These "drops" could not be attributed to regional variation observed within each depot or to growth or food intake disorders. Differences in behavior of perirenal and dorsoscapular depots were noted. The "drops" occurred earlier in perirenal than in dorsoscapular depots. The meaning of these "drops" remains unclear, but the results suggest that they may be due to a discontinuous recruitment of new observable cells. These results are discussed in relation to the hypothesis of a "critical size" of adipocytes.