The cellularity of developing adipose tissues in Pietrain and Meishan pigs.

The development of external, internal, inter- and intramuscular adipose tissues was compared in Pietrain (lean) and Meishan (obese) pigs during their growth, at 0, 7, 30 and 90 days of age. Up to 1 month of age, the total lipid content of external and internal adipose tissues as well as mean adipocyte diameter increased similarly in both breeds of pigs. The percentage of plurilocular adipocytes decreased in both breeds; it remained higher in Meishan up to 30 days of age, which would indicate a delayed maturity of adipose tissue in this pig. Adipocyte hypertrophy characterizing the Meishan pig starts between 1 and 3 months of age. At 90 days, adipocyte diameters were about 50% higher in Meishan than in Pietrain. Muscle lipid content was higher in Pietrain than in Meishan until 1 month of age, whereafter it became lower than that of Meishan. Intramuscular adipocytes appeared later than those of other tissues in both breeds and were larger in Meishan than in Pietrain.