Human myometrium - the ultrastructural 3D network of telocytes.

Telocytes (TCs), a novel type of interstitial cells, were recently described in the interstitial space of tissues (www.telocytes.com). Telocytes TCs have several very long, moniliform extensions, namely telopodes (Tps). However, the functional role(s) of TCs is not yet understood. Successive photomicrographs of ultrathin sections were concatenated to capture the entire length of Tps which usually measure tens to hundreds of micrometres. Besides the podoms (dilations) and podomers (thin segments), ultrastructural features of Tps include the dichotomous branching and establishing homo- and heterocellular contacts. Telopodes make a labyrinthine system by 3D convolution and overlapping, their number being roughly estimated at approximately 20 per 1000 μm(2) . Moreover, the presence of extracellular vesicles (shedding vesicles/exosomes) along the Tps suggests an active intercellular signalling (micro- and macromolecules), with possible significance in regulating uterine contractility.