Dynamics of the lymph nodes parenchyma relative volume of structural and functional zones in cattle (Bos taurus) in early postnatal ontogenesis

Abstract

Lymph nodes are peripheral organs of hemo- and lymphopoiesis, their parenchyma is formed by lymphoid tissue and is divided into separate structural and functional lobules, each of which, in turn, is formed by highly and low-specialized cellular zones. The dynamics of age-related changes in the relative volume of the structural and functional zones of the lymph nodes parenchyma lobules in newborn calves of 10-, 30-, 120-day-old was determined. There were examined: superficial cervical, axillary, iliac, popliteal, medial retropharyngeal, caudal mediastinal, medial iliac, iliocolic lymph nodes. The relative volume of the deep cortex central zones units, lymph nodules, interfollicular zone and medullary cords was determined on thin paraffin histosections stained with hematoxylin and eosin. In newborn calves, the lymph nodes lobules were formed, among the structural and functional zones the centers of the deep cortex units were most developed, the relative volume of which was 27–33% and the medullary cords – 21–31%, and the least ones were lymph nodules. The lymph nodules volume without light centers varied within 0.4–1.6%, with light centers – 0.3–1%. The interfollicular zone was 4–11%. During the first ten days of calf life, the greatest growth dynamics was observed in the deep cortex central zones units, the interfollicular zone, and the medullary cords. Until the age of 30 days, the dynamics of an increase in the relative volume of deep cortex units and interfollicular zone stabilized and showed a further tendency of insignificant growth. The most intense increase in the relative volume of lymph nodules was observed in 120-day-old calves. The volume of the medullary cords decreased in all the examined nodes in 30- and 120-day-old calves.