Study On The Isolated Lymphoid Follicles And Its Follicular Associated Epithelium Of The Digestive Tract Of Rabbits Of Different Ages

Isolated lymphoid follicles (Isolated lymphoid follicles, ILF) are a gastrointestinal mucosal immunity induction site, consisting of a single follicle, varied shapes and sizes, at the same time, M cells were observed in the follicular associated epithelium(FAE) of mature isolated lymphoid follicles (mILFs).This article selected 30 healthy rabbits, according to age, they were divided into three age groups, respectively, for young (2 months), pubertal (5,6and 7 months) and old (36 months), by macroanatomy, histology, PAS staining and immunohistochemical method, through a comparative study with the corresponding position of Peyer’s patch, structure of follicle associated epithelium and shape, number, development of isolated lymphoid follicles in the entire digestive tract were systematic observation and analysis. The results showed that:(1) From the esophagus to the stomach, there was no distribution of isolated lymphoid follicles in the esophagus, the stomach has abundant diffuse lymphoid tissue and a few isolated lymphoid follicles. (2) There were distributed from the cryptopatches(CP) to different developmental stages of isolated lymphoid follicles in the mesentery on the side of the rabbit small intestinal wall, mature isolated lymphoid follicles were dome shaped or oval, it was scattered to the monolayer, size was differed, compared with the corresponding parts of Peyer’s patch, the volume of mILFs was smaller than follicular volume in the PPs, but there were also similar PPs dome area. Statistical results showed that the number of mILFs in different intestinal segments was not uniform, the number of ILF in the jejunum was the most, the duodenum was the second, and the ileum was the least, from young to old, with age, the number of ILFs in the intestinal segment in correspondence was gradually increased. It was suggested that the rabbit small intestine had abundant isolated lymphoid follicles and its development with age or aging wasn t stopped, which provided the basis for the further study of rabbits and herbivorous animal small intestinal mucosal immunity. (3)ILFs were distributed in the large intestine of rabbit, and isolated lymphoid follicles were dome shaped, cylindrical or oval, cecal isolated lymphoid follicles were distributed in the lamina propria, colonic isolated lymphoid follicles were mainly distributed in the colon with mucosa lamina propria, rectal isolated lymphoid follicles were distributed in rectal distal intestinal mucosa lamina propria, showed a scattered distribution of a single, they were not of uniform size, compared with the corresponding parts of Peyer’s patch, the volume of mILFs was smaller than follicular volume in the PPs, but there were also similar PPs dome area. The distribution of isolated lymphoid follicles in the large intestine of rabbit:the number of ILF was gradually reduced from the cecum to recta. With age, the number of isolated lymphoid follicles in the large intestine of pubertal rabbits was the most, and declined subsequently. The rule of the small intestine of rabbits in different age found was different, and we speculated that this might be due to the large intestine microbes group of the pubertal rabbit tending to be stable, intestinal digestion ability was strong, and there were many harmful factors to the body. The increase in the number of isolated lymphoid follicles can effectively cause the mucosal immune response, eliminate the damage caused by harmful factors on the body. (4) The basic structure of isolated lymphoid follicle associated epithelium was similar in different intestinal segments. It was mainly composed of the absorption of epithelial cells, M cells, goblet cells and intraepithelial lymphocytes. The first type surrounded intraepithelial lymphocytes (IEL) with basolateral "pockets" and belonged to typical M cells, mainly distributed in the top area of isolated lymphoid follicle associated epithelium, but fewer. while the second type was columnar M cells which lacked "pocket" form and belonged to immature M cells. They were mainly distributed in isolated lymphoid follicle associated epithelium near the crypt in larger quantities. The distribution characteristics and the distribution characteristic of M cells in corresponding segments of PPs dome area were similar, and both of them have vimentin positive reaction. In addition, more goblet cells and intraepithelial lymphocytes can also be observed in the distribution of the FAE of the majority of ILFs, however, the FAE of Peyer’s patches were not observed in goblet cells. It was suggested that the structure of FAE of ILFs on the morphology between the absorbent of intestinal epithelium and corresponding position of FAE of PPs, it also belonged to antigen uptake sites of the digestive tract mucosal immunity. In this paper, we studied ILFs and its related epithelial cells in the digestive tract of the rabbit, and found that there were a large number of ILFs and FAE containing M cells in the digestive tract. The results of this study will be extended to the scope of the study M cells as the target of oral vaccine design and drug delivery system to provide a favorable theoretical basis.