Although the term thymic hyperplasia is used most commonly to indicate the occurrence of
germinal centers in the thymus, cognizance must be taken of the fact that such centers m. ay
occur in apparently normal thymuses in both children and adults. A concept of thymic
compartmentalization is proposed with origin of germinal centers in the perivascular space
(extraparenchymal compartment) of the thyrnus. These germinal centers contain a high
percentage of B lymphocytes in contrast to the true thymic parenchyma. Although the …