[Interstitial pacemaker cells]

This article is devoted to interstitial Cajal cells (syn. telocytes, interstitial pacemaker cells, IPC). First those cells were discovered by C.R Cajal in the muscle coat of the gut in 1893. Nowadays they have revealed in all parts of digestive systems (from esophagus to rectum), urinary and biliary tracts, prostate, liver, the walls of arteries and lymphatics, as well Fallopian tube, myometrium, mammary glands. Characteristic ultrastructural features are elongated spindle shape, length from 40 to 100 μm, the thickness of 0.2-0.5 μm, the presence of 2-5 processes. Length of them rangingfrom tens to hundreds of micrometers, some of them have secondary and tertiary branching, forming a three-dimensional network. IPC having spontaneous electrical (pacemaker) activity are cause to contraction of smooth muscle cells. Depending on the location of IPC have different morphological and ultrastructural characteristics. Characteristic immunohistochemical markers are CD117, CD34, S100, vimentin. IPC replay to acetylcholine, norepinephrine, estrogen, progesterone, and nitric oxide by influence ofcorresponding receptors. IPC have specific gap junctions with lymphocytes, basophiles, eosinophils, neutrophils, mast cells and dendritic cells. Grave pathology of those cells are forming gastrointestinal stromal tumors.