Histological and immunohistochemical findings in foetal samples. (a) Cotyledon. Diffuse and dense infiltrate of mononuclear inflammatory cells in the chorioallantoic stroma at the chorionic plate. Note the focus of mineralisation (arrowhead) HE. 15×. (b) Cotyledon. Focus of coagulative necrosis in a cotyledonary villus (arrowhead). The necrosis involves throphoblast layers and extends to the mesenchyme underneath. HE. 20×. (c) Focus of coagulative necrosis in the liver. HE. 35×. (d) Focus of coagulative necrosis in the lung (arrowhead). Note the absence of inflammatory cells. HE. 25×. (e) Placentome. Positive immunolabelling (brownish colouration) of parasitophorous vacuoles within cellular debris between foetal and maternal villi. IHC. 140×. (f) Placentome. Positive signal (brownish coloration) in the cytoplasm of macrophage-like cells within the inflammatory infiltrate in the caruncular septum. IHC. 140×. (g) Brain. Clusters of protozoal organisms immunolabelled (brownish coloration) in the neuroparenchyma with no evident necrosis or related inflammatory infiltration. IHC. 140×. Inset: detail of one of these clusters in which multiple parasite-like structures could be appreciated. IHC. 180 × .