Assessment of the Endocrine Cells and Neural Structures in the Abomasum and Pancreas of Dromedary Camel based on their Synaptophysin Immunoreactivity

Abstract

Endocrine cells of the gastrointestinal tract are located mainly within the pancreatic islets and throughout the wall of the stomach and intestines. These cells regulate several body functions via release of hormones. Synaptophysin is a transmembrane glycoprotein expressed in almost all types of endocrine cells as well as in synaptic vesicles of neurons. Nevertheless, the distribution of synaptophysin-immunoreactive (SYP-IR) cells in abomasum and pancreas of camel has not been described. In the present study, SYP immunoreaction was assessed in different regions of abomasum and pancreas of dromedary camel using SYP immunostained sections. SYP-IR endocrine cells of both closed- and open-types were observed within cardiac, fundic, and pyloric gland regions of the abomasal mucosa. Significantly higher number of SYP-IR cells were evident within the fundic and pyloric gland regions compared to cardiac gland region. Moreover, SYP labelled nerve fibers located within abomasal lamina propria and cells and fibers of the submucosal and myenteric nerve plexuses. In pancreas, SYP intensely labeled almost all cells of pancreatic islets. SYP-IR endocrine cells were also observed within the lining epithelium of pancreatic acini and ducts. In addition, SYP intensely stained cells and fibers of intrapancreatic ganglia. A moderate SYP immunoreaction was seen within the perivascular and periductal nerve fibers as well as those fibers supplying the pancreatic acini and ducts. These findings advance our understanding of the normal distribution of the gastro-pancreatic endocrine cells in camel. Future studies are needed for further characterization of hormones produced by these cells and their clinical relevance in camel.