Unique distribution of interstitial cells of Cajal in the feline pylorus

Abstract

The feline gastrointestinal (GI) tract is an important model for GI physiology but no immunohistochemical assessment of interstitial cells of Cajal (ICC) has been performed because of the lack of suitable antibodies. The aim of the present study was to investigate the various types of ICC and associated nerve structures in the pyloric sphincter region, by using immunohistochemistry and electron microscopy to complement functional studies. In the sphincter, ICC associated with Auerbach's plexus (ICC-AP) were markedly decreased within a region of 6-8 mm in length, thereby forming an interruption in this network of ICC-AP, which is otherwise continuous from corpus to distal ileum. In contrast, intramuscular ICC (ICC-IM) were abundant within the pylorus, especially at the inner edge of the circular muscle adjacent to the submucosa. Similar distribution patterns of nerves positive for vesicular acetylcholine transporter (VAChT), nitric oxide synthase (NOS) and substance P (SP) were encountered. Quantification showed a significantly higher number of ICC-IM and the various types of nerves in the pylorus compared with the circular muscle layers in the adjacent antrum and duodenum. Electron-microscopic studies demonstrated that ICC-IM were closely associated with enteric nerves through synapse-like junctions and with smooth muscle cells through gap junctions. Thus, for the first time, immunohistochemical studies have been successful in documenting the unique distribution of ICC in the feline pylorus. A lack of ICC-AP guarantees the distinct properties of antral and duodenal pacemaker activities. ICC-IM are associated with enteric nerves, which are concentrated in the inner portion of the circular muscle layer, being part of a unique innervation pattern of the sphincter.

Pyloric Resection and Delayed Gastric Liquid Emptying in Rats

“…Some scholars have argued that a connective tissue septum separates the circular muscle of the pylorus and the duodenum and blocks the spread of electrical slow waves from the stomach to the duodenum and vice versa [8,9], and other researchers believed that due to a lack of ICCs between the circular muscle and the longitudinal muscle, the pylorus blocked the slow waves propagation between the duodenum and the antrum [10].…”

“…A connective tissue septum separates the circular muscle of the pylorus and the duodenum and blocks the spread of electrical slow waves from the stomach to the duodenum and vice versa [10][11][12]. Recent evidence has suggested a discontinuity in the ICC network in the pylorus [10]. The absence of the ICC network in the pylorus allows the antrum and duodenum to have distinct motor activities [10,12].…”

“…Slow waves from the stomach or small bowel decay and die out as they conduct into this region [8][9][10]. A connective tissue septum separates the circular muscle of the pylorus and the duodenum and blocks the spread of electrical slow waves from the stomach to the duodenum and vice versa [10][11][12]. Recent evidence has suggested a discontinuity in the ICC network in the pylorus [10].…”

“…Recent evidence has suggested a discontinuity in the ICC network in the pylorus [10]. The absence of the ICC network in the pylorus allows the antrum and duodenum to have distinct motor activities [10,12].…”

“…However, there is a region of muscle at the junction between the pyloric sphincter and the duodenum that is electrically quiescent [7][8][9]. Slow waves from the stomach or small bowel decay and die out as they conduct into this region [8][9][10]. A connective tissue septum separates the circular muscle of the pylorus and the duodenum and blocks the spread of electrical slow waves from the stomach to the duodenum and vice versa [10][11][12].…”