Fig. 5

a Examples of T2-weighted MRIs at day 1 and 14 from two aged (18 months) F344 rats after intraventricular injection of blood (200 µl). In the top animal (organized hematoma), a clot remained in the right ventricle at day 14 and the ventricular system remained dilated. In the bottom animal (non-organized hematoma), the intraventricular clot resolved between day 1 and 14 and the ventricular dilatation reduced with time. Examination of the animals with H&E staining at day 14 revealed the presence of an organized clot (*) in the right ventricle in the first animal and no ventricular clot (**) in the second. Scale bar = 1 mm (left picture) and 20 mm (right picture). b Immunoreactivity for macrophage markers (Iba-1, CD68 and CD163) within the organized clot 2 weeks after IVH. Scale bar = 20 µm. c Immunofluorescence staining of alpha-smooth muscle actin (α-SMA) (fibrosis marker) at 2 weeks within the organized clot. Scale bar = 100 µm. d H&E staining showing a macrophage with hemosiderin (black arrow), neovascularization (white triangles) and hyalinization (black triangle) within the organized clot. Scale bar = 10 µm