ABSTRACT
To evaluate the effect of all trans retinoic acid [atRA] on differentiation/transdifferentiation of pancreatic duct/acinar cells into insulin secreting beta-cells in diabetic rats. 64 adult male rats divided into four groups. Normal control, diabetic control, atRA-I: diabetic rats treated with atRA [0.1 mg/kg/day, subcutaneously] and atRA-II: diabetic rats treated with atRA [2.5 mg/kg/day, subcutaneously] for 1, 2 and 4 weeks. The levels of glucose and insulin were measured. Histopathological, immunohistochemical examination of pancreas and RT-PCR of insulin mRNA were done. atRA led to an improvement in the level of glucose and insulin in both doses and at the different time points when compared with diabetic control. Histopathological examination of the pancreas revealed that atRA in both doses and at different time points nearly restored the normal appearance of the islets of Langerhans. Interestingly, some islets of Langerhans were found closely related to the interlobular ducts and the acinar epithelium. Mitotic figures were observed in the epithelium of the interlobular ducts and acinar cells and inside the islets of Langerhans especially with high dose. The immunohistochemical revealed strong insulin-immunoreactivity in the cytoplasm of the beta-cells and in the cytoplasm of the isolated cells which are closely related to the acini. Also, insulin mRNA expression showed dense band illumination similar to normal control. Retinoic acid may induced significant increase in insulin level and its mRNA, decrease glucose level and increased beta-cells regeneration through increased pancreatic duct and/or acinar cells differentian/transdifferentiation and increased proliferation of fbeta-cells in diabetic rats
ABSTRACT
The Harderian gland [HG] is a large retrobulbar, tubuloalveolar organ. It is present in many animals possessing a nictitating membrane [third eye lid]. Compare the microscopic features of the HG in the female rat [as n example of rodents] with those of the female rabbit [as an example of mammals]. Using histological, histochemical and morphometric techniques on the HG in adult female rat [3 months old] and rabbit [4.5 months old]. A total number of 6 adult animals were used in each species. By gross inspection the Harderian gland is bibbed. In the rat, the two lobes are similar in colour and texture while in the rabbit, the small lobe is white and the large lobe is red [pink]. The gland is covered by a thin C.T. capsule with species variations both in structure and auto fluorescence. In the rat the two lobes show a fundamentally similar histological structure and the secretory epithelium is formed of two types of cells, type A and type B. While in the rabbit the two lobes have different histological structure and each lobe is formed of a single type of cells that differs in both lobes. The contents of the lumina of the tubuloalveoli vary in the two species indicating different modes of secretion. Statistical difference in the arbitrary area of the tububoalveoli between the large and small lobes of the gland is insignificant in the rat but it is significant in the rabbit. In both species a single extra glandular excretory duct is detected at the hilum of the gland. In the rat the wall of the duct possess diverticula and the lining epithelium comprises some serous/or mucous acini. While in the rabbit, the structure of the duct is simple and it is lined by a low columnar epithelium with some goblet cells. Further research will be needed to correlate the different histological structure between the female rat and rabbit HG with the biology of these animals and to their functional significance