[Clinico-pathological studies on small obese mice occurring in C57BL/6J-ob/ob mice]

Eight small obese mice, 10 to 79 weeks of age, which occurred in C57BL/6J obese mice, were examined clinico-pathologically. These mice were characterized by small-sized obesity, and showed hyperglycemia without hyperinsulinemia and glucosuria without ketonurina throughout their life span. Morphologically, neither hypertrophy nor hyperplasia were found in the islets of Langerhans. There were an increase of A cells and a decrease of B cells in their islets. In the kidney, thickening of mesangial matrix in glomeruli and deposition of glycogen in the nucleus of epithelial cells of the distal tubules were seen. These findings suggest that the small obese mice are an obese-diabetic animal of different type from the usual obese mice (C57BL/6J-ob/ob). The mechanism for development of this condition was unknown.