Postnatal morphogenesis of lymph node parenchyma compartments in meat rabbit breeds

Abstract

The regularities of the formation and development of lymphoid lobules of lymph nodes parenchyma (somatic and visceral) in meat rabbits breeds during their postnatal period of ontogenesis were analyzed. We used standard histological research methods in combination with the impregnation of the midline histological sections with silver nitrate to visualize lymphoid lobules and their separate functional zones. The aim of the research was to establish the peculiarities of the histoarchitectonics of lymph nodes parenchyma in various localization according to the concept of their lobular structure in mammals and the patterns of the parenchymal lymphoid lobules transformations in the age aspect. The lymph nodes of 1-, 10-, 20-, 30-, 60-and 90-day-old meat rabbit breed (Hyplus cross) were examined. It was found that in the lymph nodes of one-day-old rabbits, the stromal component is formed by a capsule that surrounds poorly differentiated parenchymaa set of lymphoid cells and reticular fibers. Separation of lymphatic lobules and their structural and functional differentiation first appear in 10-day-old rabbits. In each lobule, units of the deep cortex (T-cell dependent zone), single lymphatic nodules (B-cell dependent zone), and medullary cords were indistinctly delimited among themselves. At the age of 20-days-old, the architectonics of lymphoid lobules was characterized by a more distinct differentiation of individual functional zones, and the number of lymphatic nodules without centers of reproduction was increased markedly. They were located exclusively at the upper pole of the lobules along the edge (subcapsular) sinusStarting from 30-days-old, at the structural and functional level of the organization, the lobules of the nodes parenchyma were completely divided into separate components: the centers of the units of the deep cortex, the paracortical and medullary cords, lymphatic nodules with and without centers, the interfollicular zone. From 60 to 90 days-old, qualitative and quantitative changes occurred in the deep cortex units, this was determined by an increase in their size, a significant increase in the number of lymphatic nodules with centers of reproduction, both on the periphery of lymphoid lobules and at the base of the medullary cords.