Figure 4.

Electron micrographs of rat pancreatic islet β-cells after exposure to 30 ng/mL fentanyl for 48 h. N: Nucleus; SG: Secretory granules; V: Vesicle; E: Endoplasmic reticulum. Chromatin margination and severe cytoplasmic vacuolization and degeneration were observed in the islets. Large and small vacuoles are present in the cytoplasm. The secretory granules and endoplasmic reticulum were much smaller than in the control group (A, × 10 000). In addition, endoplasmic reticulum and normal vesicles were almost never observed (B, × 12 000).