MORPHOLOGY OF ANTIBODY-FORMING CELLS IN YOUNG AND AGED EXPERIMENTAL ANIMALS

The morphology of the primary immunological reaction was studied in the popliteal lymph nodes of rats 6 days after immunisation with bovine serum albumin. The lymph-node indices of young animals significantly increased, and light-microscopic examination showed the activity of the germinal centers of the follicles following immunisation. These changes were not observed in old animals. Analysis of the cells of the germinal centers of the follicles by light and electron microscopy, showed immunoblasts and transitory cells in both young and old animals, but the number of cytoplasmic organelles proved to be decreased in the old animals; degenerative changes could be also observed in the cytoplasmic organelles. Mature and immature plasma cells could be found both in the young and old animals, but the number of these cells proved to be much less in the old rats than in the young ones. Earlier immunopathologic investigations of the author had also shown a decreased number of antibody-containing cells in old animals. On the basis of her experimental results, the author hypothesised inhibition of immunoblast transformation in old "animals, which may be related to the degenerative changes described; this inhibited transformation may explain the decreased number of antibody-producing cells in aged animals.