Identification of interstitial cells of Cajal in the digestive tract of turkeys (Meleagris gallopavo)

Interstitial cells of Cajal (ICCs) were identified in the digestive tract o f turkeys by electron microscopy. ICCs have been implicated as sources of p acemaking slow wave potentials that initiate peristalsis in the stomach and intestines in mammals. The gastroduodenal contraction cycle in turkeys, ho wever, is uniquely coordinated by a neurogenic pacemaker in the isthmus are a between the glandular stomach and the gizzard, and this controls the coor dinated phasic contractions of the muscles of the gizzard, duodenum and gla ndular stomach. Thus, it becomes important to look for the presence and dis tribution of ICCs in the avian digestive tract, especially in the gizzard a nd duodenum. This investigation has identified that cells are present which contain the typical characteristics of ICCs including: numerous mitochondr ia, caveolae, thin processes, basement membrane, filaments, rough ER, Golgi , and occasional gap junctions. They were mostly located in the region of t he myenteric plexus between the longitudinal and circular muscle layers and occasionally within the longitudinal muscle layer. They were frequently ne ar nerve axon bundles and were usually surrounded by collagen, elastin fibe rs, and occasional fibroblasts or blood vessels. ICCs were easily found in the ileum, but were also present in the duodenum, cecum, and rectum. None w ere found in the serosal region of the thick muscle of the gizzard. The pre sence of ICCs in the turkey duodenum, which like the gizzard is under neuro genic control, suggests that ICCs may play a role(s) in addition to initiat ing peristalsis. J. Exp. Zool. 283:426-440, 1999. (C) 1999 Wiley-Liss, Inc.