Mast cell distribution in porcine common bile duct with special reference to ghrelin

Due to the similar pattern of ghrelin localisation in human and porcine intestine, swine are described as a suitable animal model for experiments related to ghrelin and its receptors. In a previous study of ours, the presence of ghrelin immunoreactive endocrine cells in common bile duct (Ductus choledochus) (CBD) of domestic swine was established. However, data regarding the distribution of mast cell types in the CBD in this species are missing. The current study aimed to determine the distribution of tryptase-, ghrelin- and toluidine blue positive mast cells in the wall of extra- and intramural parts of porcine CBD. For this purpose, immunohistochemical staining for detection of tryptase was performed in order to identify ghrelin reactivity in mast cells. Additionally, toluidine blue staining was carried out to compare the number of metachromatic mast cells with that of tryptase positive cells. The comparative quantitative analysis showed that the number of tryptase immunorective cells was higher than that of metachromatic ones in the CBD wall. Ghrelin immunoreactive cells were the most numerous, therefore it can be assumed that not only mast cells but other cells also contain ghrelin. The three mast cells types were more abundant in the propria and subserosa of the intramural part than in the same layers of extramural CBD part. In the muscle layer, mast cell number was higher in the extramural than in the intramural part of the duct. In conclusion, taking into account the results obtained, an important role of mast cells play in controlling CBD motility and biliary gland function was suggested.