[Early lesions of pancreatic islets in small-ob mice (C57BL/6J-ob/ob)].
Pancreatic islets of C57BL/6J-ob mice were microscopically examined at the ages of 5, 13, and 21 days, to clarify the time of the increase in number of A-cells, which appears to lead to diabetic symptoms in Small-ob mice (C57BL/6J-ob/ob). The findings of islet in 5-day-old C57BL/6J-ob mice were the same as those of C57BL/6J-+/+ mice. At 13 days of age, changes in islet of C57BL/6J-ob mice were classified into 3 groups. They were no significant changes (putative normal), hypertrophic B-cells with clear cytoplasm (Ob mice), and an increase of A-cells (Small-ob mice), respectively. Electron microscopically, a tendency toward dilatation of endoplasmic reticulum was found in the hypertrophic B-cells. In the islets that had an increase in number of A-cells, only a few vacuoles, which were suggestive of degranulation, were found in the cytoplasm of B-cells, and premature secretory granules were seen in the A-cells. In part of the A-cells, development of rough-surfaced endoplasmic reticulum was also seen. Mild hypertrophy of the islets and the B-cells were observed in more non-diabetic Ob mice at the age of 21 days than non-obese mice at the same age, and only 2 of 6 mice had the increase in number of A-cells. In Small-ob mice, the increase in number of A-cells was more obvious than in the diabetic Ob mice, while other islet findings were similar to those of non-obese mice in extent.(ABSTRACT TRUNCATED AT 250 WORDS)
Uchida
K
K
Yakult Central Institute for Microbiological Research, Tokyo, Japan.
Takahashi
M
M
Nagata
Y
Y
Kimura
H
H
Funabashi
H
H
Sugiyama
M
M
D000375:Aging / Q000473:pathology*; D000818:Animals; D002452:Cell Count; D003921:Diabetes Mellitus, Experimental / Q000473:pathology; D005260:Female; D007515:Islets of Langerhans / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D008854:Microscopy, Electron