A comparison of the anatomical structure of the pancreas in experimental animals

Abstract

As basic knowledge for evaluation of pancreatic toxicity, anatomical structures were compared among experimental animal species, including rats, dogs, monkeys, and minipigs. In terms of gross anatomy, the pancreases of dogs, monkeys, and minipigs are compact and similar to that of humans. The rat pancreas is relatively compact at the splenic segment, but the duodenal segment is dispersed within the mesentery. In terms of histology, the islet of each animal is characterized by a topographic distribution pattern of α- versus β-cells. β-cells occupy the large central part of the rat islet, and α-cells are located in the periphery and occasionally exhibit cuffing. In dog islets, β-cells are distributed in all parts and α-cells are scattered in the center or periphery of the islet (at body and left lobe); whereas β-cells occupy all parts of the islet and no α-cells are present in the islet (at right lobe). Monkey islets show two distinct patterns, that is, α-cell-rich or β-cell-rich islets, and the former represent peripheral β-cells forming an irregular ring. Minipig islets show an irregular outline, and both α- and β-cells are present in all parts of the islet, intermingling with each other. According to morphometry, the endocrine tissue accounts for <2% of the pancreas roughly in rats and minipigs, and that of monkeys accounts for >7% of the pancreas (at tail). The endocrine tissue proportion tends to increase as the position changes from right to left in the pancreas in each species.

Development of an organ bath technique for isolated rat pancreas preparations to assess the effect of 1,5-AG on insulin secretion

“…A previous report showed that islets of Langerhans in the duodenal segment (right lobe) of the pancreas were more numerous than those the splenic segment (left lobe) in rats [29]. However, we confirmed that there was no significant difference in insulin levels between the right and left lobes in the ex vivo organ bath experiment.…”

“…A previous study showed that the proportion of β-cell area to total pancreatic tissue in the duodenal segment (right lobe) was higher than that of the splenic segment (left lobe) in rats [29]. Therefore, our previous study was conducted mainly using the right lobe of the pancreas [18], despite reports that in rats the number of intralobular islets in the left lobe is more than in the right lobe [19].…”

Histological and ultrastructural studies of the pancreas of native rabbits (Oryctolagus cuniculus)

“…Differently, other investigators like Dhoolappa (28) in Indian donkey and Karaca et al (29) in Van cat documented that α-cells were tend to occur in the center of the islet and β-cells towards the periphery. Tsuchitani et al (30) in minipig mentioned that both α-and β-cells were present in all parts of the islet, intermingling with each other. Kim et al (31) and Steiner et al (32) had explain that the variability of pancreatic endocrine cells distribution in different species might be due to habits of feeding, physiological functions and pathological conditions like diabetes and obesity rather than the difference in species.…”

Development of the Endocrine Pancreas in the Beagle Dog: From Fetal to Adult Life

“…In the mammalian pancreas, endocrine cells cluster into islets of Langerhans, which are embedded in the exocrine tissue and secrete insulin, glucagon, and other polypeptide hormones into the bloodstream. These islets have been extensively studied in adult mammals and are conserved across species (Steiner et al, 2010;Tsuchitani et al, 2016). The development of the fetal and postnatal endocrine pancreas has been studied in depth in rodents (Jørgensen et al, 2007) and humans (Polak et al, 2000;B eringue et al, 2002) but not in other mammals.…”