Morphological Characteristics of the Epididymal Adipose Tissue in Different Types of Hereditary Obese Mice

Abstract

The morphological appearance of both the epididymal fat pad and the subcutaneous fat depots was studied in the two strains of obese-hyperglycemic mice known as "Yellow" (YO) and "New Zealand" (NZO) obese mice. There was a rather slight increase in the relative number of mast cells in the YO-mice, compared with the very high mast cell content previously observed within the adipose tissue in other types of obesity. A larger mean fat cell volume accounted for the epididymal fat pad weight of the YO-mice being four times as great as that of their lean litter mates (YN-mice). The obesity of the NZO-mice was characterized by a pronounced fat accumulation in the epididymal fat pad, which was in this case also due to a proportionately great number of fat cells. While the NZO-mice had subcutaneous fat cells of approximately normal sixe, these cells were ten times larger in the YO- than in the YN-mice. The obesity associated with the obese-hyperglycemic syndrome in mice may be classified into an abdominal and a subcutaneous type.