Emerging diverse roles of telocytes.

Since the first description of 'interstitial cells of Cajal' in the mammalian gut in 1911, scientists have found structurally similar cells, now termed telocytes, in numerous tissues throughout the body. These cells have recently sparked renewed interest, facilitated through the development of a molecular handle to genetically manipulate their function in tissue homeostasis and disease. In this Primer, we discuss the discovery of telocytes, their physical properties, distribution and function, focusing on recent developments in the functional analysis of Foxl1-positive telocytes in the intestinal stem cell niche, and, finally, the current challenges of studying telocytes as a distinct cell type.