EFFECTS OF SCHISTOSOMAL MANSONI INFECTION ON CALOMYS CALLOSUS COELOM-ASSOCIATED LYMPHOMYELOID TISSUE (MILKY SPOTS)

Calomys callosus Rengger, 1830 (Rodentia: Cricetidae) is a mouse-like South American wild rodent, which is permissive to Schistosoma mansoni infection. In this paper we studied the effect of schistosomal infect ion in C. callosus mesenteric and omental milky spots (MS), subsidiary foci of coelom-associated lymphomyeloid tissue (CALT), during the acu te, transitional (acute to chronic), and chronic phases of the infecti on. MS were morphologically analyzed by histological methods, using br igthfield and confocal laser scanning microscopies. The MS of infected animals were mainly of lymphomyelocytic (42 to 90 days) and lymphopla smacytic (160 days of infection) types and showed frequent presence of lymphoid follicles with germinal centers, plasmacytogenesis and plasm acytosis, mastocytosis, megakaryopoiesis, erythropoiesis and less pron ounced eosinopoiesis. These results indicate that MS are a pl preferen tial site of germinal-center-dependent and independent plasmacytogenes is, and a bone marrow-like organ, committed with various cellular line ages. The consequence of C. callosus MS reactivity for schistosomal in fection is still unknown and is under investigation.