Effect of infection with Trichinella spiralis and BCG on thymic histology

The histology of mouse thymic tissue was examined following infection with Trichinella spiralis and/or BCG. ICR/CD-1 mice were orally infected with 200 T. spiralis 56 days preceding intravenous administration of 4x10-6 viable BCG. Following assessment of delayed hypersensitive foot pad reactions to BCG, the mice were bled and sacrificed. The thymus was removed from each animal, fixed in 10% neutral buffered formalin, embedded in paraffin and cut in 4 mum sections. Examination of serial sections indicated that T. spiralis and T. spiralis-BCG infections induced distinct anatomical changes within the thymic cortex and medulla, which may be related to previously described functional alterations of the immune system.