Distribution and Characteristics of Mesenteric Milk Spots in Healthy Rats and Those With Adhesion Disease

Abstract

Introduction. The adhesion process occurs in more than 80% of cases after all abdominal operations. The process of adhesion formation and, as a consequence, chronic inflammation involve the lymphoid elements (Peyer's spots, solitary follicles) present in the peritoneum and submucosa of the intestine, causing a pathological immune response. Fat-associated lymphoid clusters (FALCs), known as mammary structures, are also found in other fat reservoirs, such as the pericardium, mediastinum, and pleural cavity. The problem of visualizing milk spots in various structures of the peritoneum remains open. Relevance. Despite the fact that as early as 1921, scientists emphasized the presence of milk spots in the abdominal cavity and their great biological significance, the results of experimental studies related to milk spots are still relatively few. The novelty consists in investigating the peculiarities of the distribution of milk spots in the mesentery of the intestine with adhesion disease in rats in comparison with the health animals.
 Objective of this study is to detect milk spots, to investigate their topography and structure in the mesentery of the intestine in the health and in adhesion disease.
 Materials and methods: The experiment involved tissue preparation, macroscopic examination, histological analysis of hematoxylin and eosin-stained film preparations.
 Results. Milk spots of the intestinal mesentery in rats from the intact group are represented by round formations, 1-2 μm in diameter, white in color, uniformly and diffusely located on the area of the mesentery of the small and large intestine. Microscopically, they are characterized as a cluster of lymphocytes, plasma cells, and macrophages belonging to FALC lymphoid tissue. The area of milk spots of the peritoneum in the experimental groups varies depending on the course of the process of adhesion formation. Individual small white and gray granulations were observed in the animals of the II experimental group on the 7th day. On the 14th day of observation in the III group, the diameter of the milk spots reached 2-2.5 mm, they appeared as white granular clusters. On the 21st day, the animals of the IV group demonstrated an abundant accumulation of elliptical whitish structures, 3-4 mm in diameter near the blood vessels that differed significantly from the indicators of the other groups.
 Conclusion. The study has expanded knowledge regarding the distribution and composition of milk spots in the normal mesentery compared to those observed in adhesion disease. According to data obtained, milk spots are lymphoid tissue, represented by various types of lymphocytes, macrophages and plasma cells. The question of whether the lymphocytes found in the milk spots belong to different subpopulations, the dynamics of their number during the main stages of adhesion formation, remains an open question requiring further scientific research.