Iraqi Journal of Veterinary Sciences, Vol. 38, No. 4, 2024 (817-822) 817 Iraqi Journal of Veterinary Sciences www.vetmedmosul.com Immunohistochemical localization and distribution of Cajal cell in the intestine of rabbit A.G. Alhaaik and S.K. Mahmood Department of Anatomy, College of Veterinary Medicine, University of Mosul, Mosul, Iraq Article information Abstract Article history: Received 20 May, 2024 Accepted 14 July, 2024 Published online 26 September, 2024 A total of ten male local rabbits were used, a one centimeter was taken from the small intestine as well as from the colon. H&E and Masson's Trichrome stains were used to stain the slides. Location, shape and size, number/section in each segment of the intestine, and surface area of nerve plexuses/ μm² were studied. The CD117 was used to express the interstitial cell of Cajal (ICC). Myenteric plexus (MP) morphology and distribution in the intestine provide interpretation for intestinal peristaltic motility. The current study showed that Auerbach's plexuses (AP) had an oval or elliptical shape in the duodenum and ileum while appearing spherical in the jejunum and located either between two layers of tunica muscularis or within the internal circular muscular layer (ICML). In contrast, the AP of the colon appeared as a line of neurons in the exact location along the whole wall. ICC in this study showed high expression in the colon, whereas their expression ranged from mild to moderate in three segments of the small intestine. In conclusion, most ICC were found distributed in different locations throughout the wall of the small intestine, whereas they concentrated near MP and within ICML of the colon's wall. Keywords: Immunohistochemical Cajal cell Intestine Rabbit Correspondence: A.G. Alhaaik alhaaik_ag@uomosul.edu.iq DOI: 10.33899/ijvs.2024.150004.3676, ©Authors, 2024, College of Veterinary Medicine, University of Mosul. This is an open access article under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/). Introduction The barrier of the alimentary canal is brilliant with a compound neuronal system identified as the enteric nervous system (ENS). ENS is liable for alimentary canal movement shapes, satisfactory digestive discharge of diverse enzymes, electrolytes, and mucus, conditional on the morpho- physiological area, and coordinating the immune and protective purposes of the alimentary canal (1). The regulation of alimentary canal motility exists in stability among hormonal, myogenic, and neuronal activities. Once remote, furthermost, but not totally, areas of the digestive canal produce flowing automated movement without neuronal or hormonal stimulus. The minute electrical records are completed from the myogenically muscle sheets of various areas of the alimentary canal, flowing influenced by depolarization, named slow waves (SW), which were documented since the smooth muscle (SM) cells. Slow movement contractions are generated individually, and even though the contractions are obstructed by managers that clog (SM) voltage-dependent Ca +2 canals, the amplitudes and period sequences of SW are small. Subsequently SW was easily documented from SM cells, and it was assumed that these waves were (2-6). Consequently, it became known that the muscular barrier of the alimentary canal, comprising SM cells, contains a population of specified cells that lack contractile components. These cells are called Interstitial Cells of Cajal, and it was recommended, according to the electrophysiological works, that these cells might be pacesetter cells (7-9). Overall, ICC can be separated into two collections. In maximum areas of the alimentary canal, a skinny sheet of ICC makes a cellular web (10,11). ICCs are distributed through the alimentary canal in 2 plexuses: the Auerbach's (or myenteric) plexus, which subsumes ganglia that are located among the circular and longitudinal muscle sheet, and the Meissner's (or submucosal) plexus, that is situated among the internal muscular sheet of the submucosal and the mucosal layer (12,13). The Auerbach's