The connective connection: interstitial cells of Cajal (ICC) and ICC-like cells establish synapses with immunoreactive cells.: Electron microscope study in sity.

摘要

We present transmission electron microscope (TEM) evidence that ICC and ICC-like cells frequently establish close contacts ( synapses ) with several types of immunoreactive cells (IRC): lymphocytes, plasma cells, eosinophils, basophils, macrophages and mast cells. Such synapses were found in various organs: human mammary gland and myometrium, as well as rat stomach, gut, bladder and uterus. Specimens were observed by conventional TEM on ultrathin sections. Based on morphometric analyses and computer-aided 3-D reconstructions from serial sections, we propose an operational definition of ICC-IRC synapses: cell-to-cell close contacts where the two cells are separated by only ～15nm, equivalent to twice the plasmalemmal thickness. Two types of such synapses were found: (i) uniform ('plain') synapses (PS) - close contact extending for >200 nm, and (ii) multicontact ('kiss and run') synapses (MS) - with multiple, focal, close-contact points alternating with regions of wider intermembrane distance. For instance, a typical PS between a rat bladder ICC-like cell and an eosinophil was 2.48 μm long and 11±4nm wide. By contrast, a MS synapse in rat myometrium (between an ICC-like cell and an eosinophil) was 8.64 μm long and had 13 contact points. The synaptic cleft measured 15±8nm at contact points and ～100nm or more in wider areas. These synapses are different from gap junctions usually seen between ICC and between ICC and smooth muscle cells.