Annulate lamellae of the pancreatic exocrine cells in starved rats.

The ultrastructure of annulate lamellae in the pancreatic exocrine cells of rats starved for 3-42 days was studied. Annulate lamellae were rarely encountered in the pancreatic exocrine cells of control rats, but their incidence and size of stack was increased in those of starved rats depending on the duration of starvation, despite marked ultrastructural changes in these cells. Annulate lamellae were located in the para- or infranuclear cytoplasm of the cells and most of them were continuous with the relative normal rough endoplasmic reticulum. A close apposition in parallel was often found between the annulate lamellae and the outer nuclear envelope and occasionally pores in line with those of the nuclear membrane were observed in the lamellae of rough endoplasmic reticulum in 35- and 42-day-starved rats. An unequivocal continuity between the annulate lamellae and the nucleus and/or rough endoplasmic reticulum in pancreatic exocrine cells might be related to their origin and function.