Cellularity of bovine adipose tissue.

Subcutaneous and perirenal adipose tissue from bovine animals that had different fat deposition patterns were characterized in terms of the weight of the adipose tissue organ and adipose cell number and mean cell size as determined by electronic counting of osmium-fixed adipose cells. Similar parameters were also measured in the interfascicular adipose tissue dissected from four muscles. Adipose tissue from animals of the leaner Holstein breed contained smaller cells than the respective tissues from the fatter Hereford x Angus animals. The small subcutaneous deposit in the Holstein animals was due to a small number of adipose cells that were small in size. During growth of the bovine animal, an increase in adipose tissue mass was accompanied by cellular hypertrophy and hyperplasia. However, by 14 months of life hyperplasia was complete in all but the interfascicular adipose tissue. In the 14-month-old Hereford x Angus steers, interfascicular adipose tissue had an appreciable number of small cells and a bimodal distribution for cell diameter. The results of this study suggest that interfascicular adipose tissue is a late developing depot and that hyperplasia is still an active process in this depot at 14 months of life, whereas hyperplasia appears to be nearly complete in the subcutaneous and perirenal depots of bovine animals by about 8 months of life or shortly thereafter. Correlation coefficients indicated that intramuscular lipid content was positively related to the number of interfascicular adipose cells per 100 g of muscle in four different muscles. However, average cell diameter and volume were significantly correlated to intramuscular lipid content in only one of the four muscles studied.