Identification and characterization of telocytes in the uterus of the oviduct in the Chinese soft-shelled turtle, Pelodiscus sinensis: TEM evidence

Abstract

Telocytes (Tcs) are cells with telopodes (Tps), which are very long cellular extensions with alternating thin segments (podomers) and dilated bead-like thick regions known as podoms. Tcs are a distinct category of interstitial cells and have been identified in many mammalian organs including heart, lung and kidney. The present study investigates the existence, ultrastructure, distribution and contacts of Tcs with surrounding cells in the uterus (shell gland) of the oviduct of the Chinese soft-shelled turtle, Pelodiscus sinensis. Samples from the uterine segment of the oviduct were examined by transmission electron microscopy. Tcs were mainly located in the lamina propria beneath the simple columnar epithelium of the uterus and were situated close to nerve endings, capillaries, collagen fibres and secretory glands. The complete morphology of Tcs and Tps was clearly observed and our data confirmed the existence of Tcs in the uterus of the Chinese soft-shelled turtle Pelodiscus sinensis. Our results suggest these cells contribute to the function of the secretory glands and contraction of the uterus.

Keywords: Chinese soft-shelled turtle (Pelodiscus sinensis); telocytes; ultrastructure; uterus.

Fig. 1

Digitally coloured TEM image of the turtle uterus. Long telopodes are present around the capillary. The podom and a telocyte are also visible. (Tc, telocyte; Tp, telopode; RBC, red blood cell; En, endothelium). The scale bar represents 5 μm.

Fig. 2

Digitally coloured TEM image of the turtle uterus (enlarged rectangular area of Fig. 1) showing a telocyte with its long telopodes. Circular areas show the close connection of telopodes with collagen fibres. The telopode is very long with alternating podom and podomer. The mitochondria are also visible. (Tc, telocyte; Tp, telopode; Pd, podomer; N, nucleus; M, mitochondria; Cf, collagen fibres). The scale bar represents 2.5 μm.

Fig. 3

Digitally coloured TEM image of the turtle uterus. At least 2 telocytes with their extensive telopodes are visible in the lamina propria near gland cells. Telopodes with long alternating podom and podomer are visible. (Tt, tortuous telopode; Tc, telocytes; GC, gland cells; Pm, podom; Pd, podomer). The scale bar represents 2 μm.

Fig. 4

Digitally coloured TEM image of the turtle uterus. Two telocytes are clearly visible and telocytes connect with telopodes from other telocytes. The encircled area shows the close connection between telopodes. Mitochondria and vesicles are also visible. (TC, telocyte; Tp, telopode; GC, gland cell; CC, close connection; Ve, vesicle; M, mitochondria). The scale bar represents 2 μm.

Fig. 5

TEM image of the turtle uterus. The encircled area shows the close connection of telopode with smooth muscle. Ectosomes (digitally coloured violet) and rough endoplasmic reticulum are visible. (Tc, telocyte; RER, rough endoplasmic reticulum; Et, ectosomes). The scale bar represents 1 μm.

Fig. 6

Digitally coloured TEM image of the turtle uterus. The telocyte and telopode exist in the uterine lamina propria in close proximity to gland cells and form a labyrinthine structure. Gland cells, telopodes, podom and podomer are visible. (M, mitochondria; Pm, podom; Tp, telopode; Pd, podomer; GC, gland cells). The scale bar represents 5 μm.

Fig. 7

Digitally coloured TEM image of the turtle uterus. A telocyte is visible in close proximity to a nerve. (N, nerve; Tc, telocyte; Tp, telopodes; SM, smooth muscle). The scale bar represents 2 μm.

Fig. 8

Digitally coloured TEM image of the turtle uterus. A telocyte with a convoluted telopode can be seen near the gland cells and collagen fibres. (Tc, telocyte; Cf, collagen fibres). The scale bar represents 5 μm.

Fig. 9

Digitally coloured TEM image of the turtle uterus. A telocyte with long thin telopode and podom is clearly visible near to the collagen firers. (Tc, telocyte; Tp, telopode; Pm, podom; Cf, collagen fibres). The scale bar represents 5 μm.

Fig. 10

Digitally coloured TEM image of the turtle uterus showing typical telocyte and telopodes connected with collagen fibres. (N, nucleus; C, cytoplasm; Tp, telopode; Pm, podom). The scale bar represents 1 μm.

Fig. 11

Digitally coloured TEM image of the turtle uterus. Telocytes with long telopode are visible around the gland cells and blood vessel form a labyrinthine structure. Gland cells, telocytes, telopodes are prominent. (GC, gland cells; Tc, telocyte; Tp, telopode). The scale bar represents 5 μm.