Liver and spleen histological sections from Syrian hamsters stained with H&E. (A) Uninfected hamsters show normal liver histological sections (×40). (B) Hamsters infected with 105 L. infantum parasites show granuloma reactions after three months pi (×40). Compare (A) with (B). (C) Granuloma formation. Initial parasitization of KCs (arrows) surrounded by a few inflammatory cells (lymphocytes and monocytes), showing the lack of organization after three months pi (×400). (D) Developing granuloma and giant cells containing few residual amastigotes after three months pi (×400). (E) Normal splenic architecture in control hamsters (×40). (F) Disruption of the splenic architecture accompanied with lymphoid depletion in hamsters infected with 107 L. infantum promastigotes after three months pi (×40). Compare (E) with (F). Hamsters and BALB/c mice were purchased from Harlan Interfauna Ibérica S.A. (Barcelona, Spain). The animals were maintained under conventional conditions approved by the Ethical Committee for the Animal Experimentation of the Complutense University of Madrid.