Histological study of pancreas revealed that endocrine tissues in both groups of normoglycemic rats formed the islets of Langerhans, which were scattered throughout the pancreatic tissues. They accounted for about 10% of all pancreatic tissues. β-cells (insulinsecreting cells) were found in the central region of the islets, while α–cells (glucagon-secreting cells) were found at the peripheral region (Fig 2 A and B). Severe destruction of β-cells was found in the diabetic rats. Only a small area of islets of Langerhans were present and both β- and α–cells could rarely be seen. Pyknotic nuclei were detected in some β-cells (Fig 2C). The islets of Langerhans of the diabetic rats treated with T. laurifolia extract were larger than the untreated group and more β-cells were also found (Fig 2 D). The numbers of islets of Langerhans in the normoglycemic groups were, however, higher than those of treated and untreated diabetic groups.