Figure 3: Splenic fibrosis observed after repeated immunizations with recombinant PfP0. (a) Spleen of control mice. (b) Spleen of a mouse following repeated immunization with recombinant PfP0 (four weekly and seven monthly). Arrows point to the spleen. Note the reduced size of the spleen and fibrosis around it. Histopathological analysis revealed a loss of lymphoid cells and extensive replacement of splenic tissue with connective tissue.