Study On Distribution And Infrastructure Of The Telocytes In Stomach Wall Of Andrias Davidianus

Telocytes(TCs) are a novel interstitial cell with special structure characteristics. They play a critical role in many physiological processes, such as tissue regeneration, repair and intercellular communication. Therefore, TCs has become a research hotspot in the regenerative medicine and translational medicine. Currently, the studies regarding TCs mainly focus on higher mammals, e.g. human and murine. Moreover, TCs have been identified in various tissues and organs of mammals. However, the knowledge regarding lower animals TCs remains rare. Chinese giant salamander(Andrias davidianus), a large size amphibian, is included in the critically endangered animals of IUCN because their wild population are rare. Consequently, the investigations regarding organs TCs of A.davidianus is of great significance in revealing physiological and pathological roles of TCs,disclosing mechanisms of amphibian organ regeneration, protecting and using rationally the amphibian. Also, it provides clinical reference for the diagnosis and treatment of related diseases.In the present study, we employed classical histological staining(HE, MTB and Ag-NORs), immunohistochemisty(IHC) and transmission electron microscopy(TEM)methods to identify gastric wall TCs of the A. davidianus. The hematoxylin and eosin(HE)staining showed that the gastric wall consists of four layers, i.e. mucosa, submucosa,muscularis and serosa. The mucosa was divided into three layers, which are epithelium,lamina propria and muscularis mucosa, respectively. A lot of mucous glands and gastric glands were observed in lamina propria. The submucosa was very thin. The muscularis was very thick and filled almost half the gastric wall. The TCs with very long and thin telopodes(Tps) were located in stroma between gastric glands. The cell bodies TCs mostly exhibited spindle-shaped and polygonal. The long Tps of TCs frequently clinged to the funds of gastric glands and blood vessels. IHC showed that c-kit~+, CD34~+ and PDGFR?~+TCs are widely located in the stroma of gastric wall and close to blood vessels. The cell bodies of TCs appeared spindle-shaped and polygonal as well as in the classical histological staining. The TCs also possessed 1–3 very thin and long Tps, which showed moniliform because of the alternative podoms and podomers. Moreover, the podoms showed strong positive IHC staining. In addition, TEM microphotos also demonstrated the presence of TCs with very thin and long Tps in connective tissue between gastric glands.The cell bodies of TCs exhibited pyriform, spindle-shaped and trigonal. Likewise, TCs/Tps were located adjacent to gastric glands and blood vessels. Especially, TCs were found in close proximity to an endocrine cell. TCs were frequently observed adjacent to stem cells,and their Tps surrounded the stem cells. TCs and Tps, Tps and stem cells established close contacts. Moreover, the shed vesicles and exosomes were also detected near TCs/Tps.In conclusion, we confirm the presence of TCs in the amphibian stomach wall. In particular, we identified gastric TCs by TEM and disclosed the ultrastructural relation of TCs and other resident cell types, such as gastric glands, stem cells and endocrine cells.These results suggest that TCs play a role in regulating other types of cells regeneration and homeostasis. Our study will improve the insight of TCs functions in amphibian stomach and disclosing mechanisms of amphibian organ regeneration. Our study also provides clinical reference for the diagnosis and treatment of stomach diseases.