PATHOLOGICAL-CHANGES IN THE LYMPHORETICULAR TISSUES OF SWISS MICE INFECTED WITH ECHINOCOCCUS-GRANULOSUS CYSTS

Swiss mice infected i.p. with approximately 1500 protoscolices of E. granulosus and sacrificed at 3 and 13 mo. post infection [p.i.] yielded both viable and degenerated hydatid cysts. The mean cyst weights in the 3 and 13 mo. p.i. mice were 0.13 and 2.1 g, respectively. Sections of spleens and lymph nodes in the 3 mo. p.i. mice showed hyperplastic follicles and blastoid cells in thymus dependent areas. At 13 mo. p.i. T [thymus derived] cells from paracortex and periarterial areas were replaced by plasma cells and confluent sheets of histiocytes; follicles retained germinal centers and medullary areas showed intense plasmacytosis and sinus histiocytosis. Failure of mice to control the histogenesis of hydatid cyst with reference to numerical reduction in T cells is discussed.