Ultrastructural changes in mouse Leydig cells after streptozotocin administration.

Male ICR mice were intraperitoneally injected with a single dose (100 mg/kg BW) of streptozotocin (STZ). The pancreas and testis were excised at 1, 2 or 4 weeks after STZ administration and observed by light and electron microscopy. At 2 weeks after injection (p.i.), the islets of Langerhans in the pancreas showed severe atrophy, indicating a diabetic state. In the testis, although no conspicuous morphological changes were detected at 2 weeks p.i., noticeable changes had occurred in the Leydig cells at 4 weeks p.i. In the cells, lipid droplets increased in number, whereas smooth endoplasmic reticulum (sER) decreased. Giant whorl-like sER appeared frequently at this time. These findings indicate the declined secretory activity of Leydig cells in STZ diabetic mice.