Fig. 6
Comparison of ST-ISODATA designated abnormal tissue signatures with histology. H&E stained brain sections from animals with permanent (pMCAo1: I.a, c and pMCAo2: I.b, d) or 3-h transient (tMCAo1: II.a–d) MCAo. Insets display the 240 h T2 MRI with overlays of Signatures I (green), II (red), III (yellow), IV (blue), and V (orange), and a squared box indicating the area of the microscopic fields. In permanent MCAo, most severe tissue injury was observed in Signature II regions (I.a, b) that corresponded with severe tissue necrosis and loss, sheets of activated, vacuolated microglia/macrophages (gitter cells, thin arrows) and some remaining vasculature. Neuronal and glial injury and degeneration in the peri-lesional brain regions corresponded with Signature III, and included degenerated axons (spheroids, I.c, thin arrows) and hypereosinophilia of dying neurons (I.d, thin arrows). In transient MCAo Signature I (II.a) corresponded with areas with peri-lesional neuronal mineralization (fat arrows) and astrogliosis evidenced by the presence of numerous, large eosinophilic gemistocytes (thin arrows). Signature IV (II.b) corresponded with brain regions with vascular proliferation, spongiosis, and marked astrogliosis. Signature V (II.c) corresponded with brain regions with necrosis and infiltration of gitter cells. The border region between Signatures IV and V is displayed in lower magnification in II.D (×10). Original magnification ×20 (I.a–d; II.a–c)