Cellularity of bovine adipose tissues: developmental changes from 15 to 65 percent mature weight.

Changes in the cellularity of various adipose tissues in growing cattle were analyzed. Fifty male cattle were slaughtered between 15 and 65% of mature weight. The whole adipose mass, separated by dissection, was divided into three parts: subcutaneous, intermuscular, and internal adipose tissues. Lipid content, cell size and distribution, as well as cell number of these three parts were determined. Adipose cells became 15 times greater from 15 to 65% mature weight, whereas total adipose cell number increased only 1.8-fold. However, a significant hyperplasia occurred near 45% mature weight. These results suggested a cell size regulation by hyperplasia. Over the whole period studied (15-65% mature weight), hyperplasia was far higher in subcutaneous adipose tissue than in other tissues. This is discussed as related to the higher relative growth of this tissue. In each fatty tissue, two identical development periods were observed. Each of them began by an increase in small-sized cells (hyperplasia) followed by the filling of these cells (hypertrophy). These two periods were particularly clear in the case of subcutaneous tissue, in which the second hyperplasia occurred slightly later than in other fatty tissues. So, in all respects, subcutaneous fatty tissue appears to develop later than other tissues studied.