Telocytes in pancreas of the Chinese giant salamander (Andrias davidianus)

Abstract

Telocytes (TCs), novel interstitial cells, have been identified in various organs of many mammals. However, information about TCs of lower animals remains rare. Herein, pancreatic TCs of the Chinese giant salamanders (Andrias davidianus) were identified by CD34 immunohistochemistry (IHC) and transmission electron microscopy (TEM). The IHC micrographs revealed CD34+ TCs with long telopodes (Tps) that were located in the interstitium of the pancreas. CD34+ TCs/Tps were frequently observed between exocrine acinar cells and were close to blood vessels. The TEM micrographs also showed the existence of TCs in the interstitium of the pancreas. TCs had distinctive ultrastructural features, such as one to three very long and thin Tps with podoms and podomers, caveolae, dichotomous branching, neighbouring exosomes and vesicles. The Tps and exosomes were found in close proximity to exocrine acinar cells and α cells. It is suggested that TCs may play a role in the regeneration of acinar cells and α cells. In conclusion, our results demonstrated the presence of TCs in the pancreas of the Chinese giant salamander. This finding will assist us in a better understanding of TCs functions in the amphibian pancreas.

Identification of Telocytes in the Pancreas of Turtles—A role in Cellular Communication

“…Our results clearly show the existence of long, convoluted, and moniliform Tps. Previous investigation showed that TCs are present in the pancreas of several mammals, cats, rats, degus, and humans [13,19,30,43]. In this study, we demonstrated the presence of TCs within the connective tissue in between the lobules and gland cells in the pancreas of Chinese soft-shelled turtles by TEM, IHC, and IF, according to the TC diagnostic criteria.…”

“…Furthermore, TCs secrete extracellular vesicles that play an important role in supporting tissue repair/regeneration and nurse function, intercellular signaling, cell differentiation [16], homeostasis maintenance, and transport and release of lipids, proteins, as well as nucleic acids, in order to meet the target tissue requirements [17][18][19][20][21]. This communication is achieved by releasing the microRNA-filled extracellular vesicles from TCs/Tps to regulate cell functions [22].…”

“…Although protein gene product 9•5 (PGP9.5) is a specific tissue marker for the neuroendocrine system and for certain tumors of the lung, colon, and pancreas, a study revealed that CD34, vimentin, tyrosine kinase receptor (c-kit), and PGP 9.5 can be used for TC identification [4]. TCs have been found in the interstitial spaces of the following major organs; namely, intestine [23], lungs [17,24], heart [25], trachea [24,26], parotid glands [27], pulmonary veins [28], pleura [17], skeletal muscle [29], pericardium [25], exocrine pancreas [13,19,30], mesentery [31], gall bladder, placenta [7,32,33], mammary gland, blood vessels [34][35][36][37], uterus, fallopian tube, female reproductive duct [38,39], endometrium [40], and myometrium [41,42]. TCs have been identified in various mammalian species, including humans, pigs, canines, rats, gerbils, mice, and degus [1,6,43,44].…”

“…TCs have been identified in various mammalian species, including humans, pigs, canines, rats, gerbils, mice, and degus [1,6,43,44]. However, there are few studies regarding the characterization of TCs in lower animals like zebrafish, chickens, turtles, and newts [5,19,45]. Extracellular vesicles (EVs) or shade vesicles are nano-sized membrane-bound vesicles that originate in the endosomal compartment.…”

“…Therefore, soft-shelled turtles have been used in the field of research as a model animal, in order to provide analysis of the characteristics and functional genes involved in various biological and stress processes [55][56][57]. Furthermore, the pancreas is a crucial vital organ, and ultrastructural and immunophenotyping studies for localization of TCs in the turtle pancreas might suggest the role of these cells in multiple ways, including regeneration/repair, as carriers of information to the neighboring cells, and immune functions [19]. TCs share organ specific characteristics among different species [5,13], similar functions of TCs may be expected in mammals.…”