[Mast cell changes in the organs of the immune system under physical loading]

By means of histological and morphological methods reaction of mast cells has been studied in the thymus and inguinal lymph nodes of mature non-inbred white male rats, subjected to systematic physical loadings (daily swimming) with increasing time from 5 up to 100 min during 5 months. Morphological changes in the organs studied and manifestation of the mast cell reaction essentially depend on the degree of the animals' adaptation to the loading. In the animals adapted to swimming, decreasing area, occupied by the connective tissue elements, in comparison to that in the control--increasing cortical area, increasing number of lymphoid cells, decreasing number of the mast cells in the inguinal lymph nodes--are noted. When the adaptation of the animals to the loading is insufficient, outgrowth of the connective tissue elements, decreasing cortical zone, impoverishment of the parenchyma with lymphocytes occur. The number of the mast cells increases, many of them are at the state of degranulation.