Lymphoid plaques of the small intestine

Lymphoid plaques (noduli lymphoidei aggregati), or, as they are also called, Peyer's plaques, are nodular clumps of lymphoid tissue. Plaques are located in the walls of the small intestine, mainly its terminal part - the ileum, in the thickness of the mucosa and in the submucosa. In these places, the muscular plate of the mucous membrane is interrupted or absent. Lymphoid plaques have the appearance of flat formations, mostly oval or round, slightly protruding into the lumen of the intestine. Plaque is located more often on the side opposite the mesenteric margin of the intestine, in some cases - near the mesenteric edge of the intestine. The long-sized plaques are oriented, as a rule, along the intestine. There are plaques lying obliquely in relation to the gut length or even in the transverse direction. The latter are occasionally located at the most terminal part of the ileum, near the ilio-cecal valve. Circular folds of the mucosa in the place of lymphoid plaques are interrupted. Plaques are located almost next to each other, sometimes the distance between them reaches several tens of centimeters. The number of lymphoid plaques during their maximum development (in children and adolescents) is 33-80.

The length of lymphoid plaques varies within wide limits - from 0.2 to 1.5 cm, the width does not exceed 0.2-1.5 cm. The mucous membrane of the ileum in the region of lymphoid plaques is uneven, bumpy. Between the tubercles, the transverse dimensions of which reach 1-2 mm, there are small indentations.

Lymphoid plaques from lymphoid nodules are constructed, the number of which in one plaque ranges from 5-10 to 100-150 and more. Between the nodes there are diffuse lymphoid tissue, thin bundles of connective tissue fibers. Between the individual nodules are found intestinal glands. Often, the nodules lie on top of each other in two rows. Dimensions of lymphoid nodules that form plaques in children, adolescents and young men range from 0.5 to 2 mm. The central part of most nodules is occupied by a large breeding center.

[1], [2], [3], [4], [5], [6]

Development and age specific features of lymphoid plaques of the ileum

The accumulation of cells of the lymphoid series in the thickness of the terminal section of the small intestine can be detected in the fetus on the 4th month of intrauterine life. The boundaries of the future nodules are indistinct, the cellular elements in them are located loosely. The intestinal mucosa in these areas is thickened. In a 5-month-old fetus, nodules in the mucous membrane become rounded, and their contours are more decorated. The size of lymphoid ileum plaques in fetuses does not exceed 2 cm in length and 0.2 cm in width, their number before birth varies from 5 to 21. In newborns, these plaques do not yet protrude above the surface of the mucous membrane. The number of them reaches 30, and the length of the largest of them is 2-3 cm. In single knots that are part of the plaques, there are already breeding centers. As the child's age increases, the number of nodules containing the center of reproduction increases rapidly. In children at the age of 1, lymphoid plaques already protrude above the surface of the mucous membrane. After 20 years and especially in people older than 30 years, the borders of lymphoid plaques are less visible on the surface of the mucous membrane, and after 40-50 years the surface of the mucosa over the plaques is smoothed.

The number of lymphoid plaques decreases with age. In people over the age of 40, the number of plaques does not exceed 20, and over 60 years - 16. The sizes of plaques and the number of lymphoid nodules in their composition are reduced. After 50-60 years, breeding centers in lymphoid nodules are rare.

[7], [8], [9], [10], [11]