Interstitial cells of cajal in the canine colon: A special communication network at the inner border of the circular muscle

Abstract

The ultrastructure of the region shown to be essential for pacemaking activity of the circular muscle of the canine colon was studied. This region, at the inner border of the circular muscle, consists of a network of several layers of interstitial cells of Cajal type III. These are interconnected to one another and to the adjacent circular muscle cells by numerous gap junctions. Elsewhere in circular muscle, gap junctions are rare and small. In addition, interstitial cells are in close (often less than 20 nm) contact with nerve varicosities containing large granular vesicles or sometimes small granular vesicles. The morphology of interstitial cells resembles that of others of type III. It is suggested that this arrangement of interstitial cells, circular smooth muscles, and nerves allows for a tightly coupled network of membrane oscillators to be subject to neural modulation.

Inward rectifier potassium conductance regulates membrane potential of canine colonic smooth muscle

“…This region contains a population of interstitial cells of Cajal thought to be the pacemakers (Berezin et al 1988;Langton et al 1989). We also tested the effects of Ba¥ on preparations in which the submucosal pacemaker cells were removed by dissection (ICM).…”

The Inner Sublayer of the Circular Muscle Coat in the Canine Proximal Colon: Origins of Spontaneous Electrical and Mechanical Activity.

“…The submucosal border of the inner circular muscle coat produces electrophysiological events called slow waves, which are synchronized with mechanical contractions of this tissue (BARAJAs-LoPEz et al, 1989;CONKLIN and DU, 1990;SANDERS et al, 1990;SERI et al, 1990). Previous electron microscopic studies have shown that there are layers of special cells connected with each other by gap junctions (BEREZIN et al, 1988). These cells formerly were generally referred to as the interstitial cells of Cajal (ICCs) (BEREZIN et al, 1988;WARD and SANDERS, 1990).…”

“…Previous electron microscopic studies have shown that there are layers of special cells connected with each other by gap junctions (BEREZIN et al, 1988). These cells formerly were generally referred to as the interstitial cells of Cajal (ICCs) (BEREZIN et al, 1988;WARD and SANDERS, 1990). However, the cytological differences between these cells and the cells called ICCs in rodents (COOK and BURNSTOCK,1976;THUNEBERG, 1982THUNEBERG, , 1989 were so great that discrepancies occurred concerning which kinds of cells were actually being investigated.…”

Projections of substance P, vasoactive intestinal peptide and tyrosine hydroxylase immunoreactive nerve fibres in the canine intestine, with special reference to the innervation of the circular muscle.

“…This nerve plexus was described by STACH (1972) and called the plexus entericus extremus, a terminology subsequently adopted by other authors (FAUSSONE PELLE-GRINI, 1983;CHRISTENSEN and RICK, 1987). The canine colon does not have an inner layer of specialized smooth muscle and, similar to most other mammals, has a dense plexus of nerve fibre bundles at the surface adjacent to the submucosa (BEREZIN et al, 1988).…”