Telocytes: novel interstitial cells present in the testis parenchyma of the Chinese soft‐shelled turtle Pelodiscus sinensis

Abstract

Telocytes (TCs) are novel interstitial cells that have been found in various organs, but the existence of TCs in the testes has not yet been reported. The present ultrastructural and immunohistochemical study revealed the existence of TCs and differentiate these cells from the peritubular cells (Pc) in contact with the surrounding structures in the testes. Firstly, our results confirmed the existence of two cell types surrounding seminiferous tubules; these were Pc (smooth muscle like characteristics) and TCs (as an outer layer around Pc). Telocytes and their long thin prolongations called telopodes (Tps) were detected as alternations of thin segments (podomers) and thick bead‐like portions (podoms), the latter of which accommodate the mitochondria and vesicles. The spindle and irregularly shaped cell bodies were observed with small amounts of cytoplasm around them. In contrast, the processes of Pc contained abundant actin filaments with focal densities, irregular spine‐like outgrowths and nuclei that exhibited irregularities similar to those of smooth muscle cells. The TCs connected with each other via homocellular and heterocellular junctions with Pc, Leydig cells and blood vessels. The Tps of the vascular TCs had bands and shed more vesicles than the other TCs. Immunohistochemistry (CD34) revealed strong positive expression within the TC cell bodies and Tps. Our data confirmed the existence and the contact of TCs with their surroundings in the testes of the Chinese soft‐shelled turtle Pelodiscus sinensis, which may offer new insights for understanding the function of the testes and preventing and treating testicular disorders.

Presence, localization and morphology of TELOCYTES in developmental gonads of fishes

“…In addition to that the location of our CD34 positive telocytes, in testis of fish, are in line with the previous study in testis of turtle (Yang et al, ) and human (Marini et al, ), which gives the evidence that CD34‐positive stromal cells were distributed in the outer layer of seminiferous tubules and between tubules or around Leydig cells in a reticular network in these gonads, with potential implications in tissue homeostasis and in the physiological processes of the testes (Marini et al, ).…”

“…Ultrastructural evidences of telocytes in ileum were found in the Chinese giant salamander Andrias davidianus (amphibian; Zhang et al, ). In the reptile Pelodiscus sinensis , known as Chinese soft‐shelled turtle, novel interstitial cells were found in the testis of the males (Yang et al, ), and similar cells were observed in the uterus of the oviduct in the female these animals (Ullah et al, ). These authors suggest that these cells contribute to the function of the secretory glands and contraction of the uterus of the turtle.…”

“…Besides that, the positive detection for two proteins (Vimentin and CD34 protein) that characterize mesenchymal cells by immunohistochemistry and immunofluorescence techniques, in the same cell type, associated with its morphological characteristics, allows the conclusion that it is really a telocyte. These cells, in addition to expressing proteins typical of mesenchymal cells, as they are considered, also present a typical morphology of mammalian telocytes, which are provided with cellular extensions called telopodes (Popescu, ; Popescu & Nicolescu, for review) and reptiles telocytes (Yang et al, ).…”

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

“…In the last 10 years, TCs have been identified in many organs of various animals, especially in mammals, including human, pig, gerbil, mouse, rat, degu and canine [1,2,4,[13][14][15][16][17]. There are also a few studies regarding TCs in lower animals, such as the newt, zebrafish, turtle and chicken [2,[18][19][20]. TCs have become an important research focus in cell biology and translational medicine.…”

“…Finally, the sections were photographed by BM 2000 light microscopy (Yongxin, Nanjing, China). TEM was conducted according to the methods of Yang et al [20] and Zhang et al [22]. Briefly, small pieces of pancreas tissue were fixed in 2.5% glutaraldehyde/PBS (pH 7.4, 0.1 M) at 4°C for 72 hrs, and then they were fixed later in 1% OsO 4 (Polysciences Inc., Warrington, PA, USA) for 1 hr, dehydrated in a concentration series of ethanol, infiltrated with propylene oxide/araldite mixture and embedded in araldite.…”