Restriction of regenerative capacity of the rat thymus after the application of cyclophosphamide

Restriction of thymic regenerative capacity, in contrast to the data in the literature, was found 30 days after a single (300 mg per kg) or fractionated doses (5 x 60 mg per kg) of Cyclophosphamide. Detailed cellular analysis revealed myelometaplastic changes in the thymic parenchyma, especially in the outer cortex and cortico-medullary zone. Plasmoid elements also appeared in the outer cortex. The capsular and septal connective tissue was markedly thickened. The thymic mass was decreased. The changes were more marked after the fractionated than after the single dose of Cyclophosphamide.