Morphological characteristics and distribution identification of telocytes in Tibetan sheep testis and epididymis

Telocytes (TCs) are a type of stromal cell discovered in the various organs of different animals and have many potential functions, including angiogenesis, signalling, and substance transport. However, the TCs have not been detected in the testis or epididymis of Tibetan sheep. This study investigated the position, characteristics, and distribution of TCs in the testis and epididymis of Tibetan sheep using transmission electron microscopy (TEM), toluidine blue staining, immunohistochemistry, and double immunofluorescence to elucidate their possible functions. TEM revealed that TCs were often found near basement membranes and capillaries and were characterised by large nuclei, elongated cytoplasmic protrusions, and many secretory vesicles. We also observed via toluidine staining that TCs were present near basement membrane and interstitial capillaries. Immunohistochemistry and double immunofluorescence revealed the positive expression of CD117, vimentin, platelet derived growth factor receptor α(PDGFRα), PDGFRα + CD117, and PDGFRα + vimentin in TCs. Additionally, we inferred that TCs participates in the formation of the blood–testis and blood–epididymis barriers, as well as in material transport and a stable microenvironment. This study presents the first evidence of the presence of TCs near the basement membrane and blood vessels in the testis and epididymis of Tibetan sheep. These findings provide new insights into the function of TCs in the reproductive systems of plateau animals.