The Histologic Structure Of The Smooth Muscle Of The Pars Pylorica In Rabbit, Dog And The Pig

In order to get the histologic structure of the smooth muscle of the pars pylorica in rabbit , dog and the pig , the structure of the smooth muscle of the pars pylorica in ten rabbits , ten dogs and ten pigs were respectively observed by using the paraffin method . The histologic characteristics of the smooth muscle of the pars pylorica in three animals was gotten by analyzing the relationship between the smooth muscle of the pars pyloric and the divison and function of the pars pyloric as well as the mechanism of switching and so on. The results were as following:The pars pylorica was divided into the pylorus proximate, pyloric antrum and pylorus distance based on the thickness and the kinds of the smooth muscle in three animals. The thickness of the smooth muscle in the pylorus proximate was thinner than that in other two regions, both outer longitudinal and inner circular layers of smooth muscle were observed in the proximal pylorus of the curvatura ventriculi major in rabbit and pig, the outer longitudinal smooth muscle decreased gradually along the parietal and visceral surface which was disappeared in the curvatura ventriculi minor, there was the similarity on four facies in the proximal pylorus of the curvatura ventriculi major in dog– the organized outer longitudinal and inner circular layers of smooth muscle was observed.The thickness of the smooth muscle in pyloric antrum in three animals increased forming the prepyloric sphincter, the average thickness of which was 3.3cm. The prepyloric sphincter consisted of the outer longitudinal musle and the inner circular musle in dog, the prepyloric sphincter consisted of the circular muscle in other facies in rabbit and pig except the curvatura ventriculi major in which the thickness of musle was because of the outer longitudinal musle and the inner circular musle .The thickness of the smooth muscle in pylorus distance in three animals increased forming the pyloric sphincter, the average thickness of which was 5.1cm, both the regular outer longitudinal and inner circular layers of smooth muscle were still observed on every facies except for the curvatura ventriculi minor where the complexity of the lamina muscularis emerged: the intermedial circular muscle was wavilness and became oblique towards the mucous membrane in rabbit; The collagen fibers among the circular muscle were observed which was parallel to the muscle fibers or inserted into the muscle fibers forming the network structure in dog; The two muscle fibers with special direction were interlaced forming the network structure in pig . the prominent feature was the appearance of the torus pyloricus from the pyloric antrum to the pylorus distance in the curvatura ventriculi minor in pig, the distribution of the lamina muscularis in which was irregular and the muscle fibers was observed on the submucosa.The results have suggested that the traditionary description on the histologic structure of the smooth muscle of the pars pyloric have some limitation , that is , the distribution of the muscular layers in pars pyloric is not integrated, only two layers or even one layer muscle can be observed in some parts , which coincide with the discovery of the clastic anatomy of gastric muscular layers in animals and also provided the information for the observers of the gastric pyloric movement . There is very important relationship between the distribution of the lamina muscularis and the division of the pars pylorica as well as the switching of the pars pylorica , it also represent an important part of the mechanism which controls gastric emptying and also prevent the reflux of duodenal content.