Figure 6.

Hematoxylin and Eosin (H&E) staining of the brain of SHRSP demonstrates CSVD lesions including extravasation of red blood cells and microbleed formation (A–C), hemosiderin deposition (D–F), thickening and hyalinization of vessel wall (G–L), and enlargement of the perivascular spaces (M–O). Sections were obtained from the mid sagittal brain area at the level of the dorsal and ventral hippocampus and images were captured at (20X) magnification. Early red blood cells extravasation is encountered consistently at 16 weeks of age [arrow in (A)] which increases in size with age at 24 weeks [arrow in (B)] and 32 weeks [arrows in (C)]. Hemosiderin disposition is seen later in life at 24 weeks [arrows in (D) and (E)] and it increases in size at 32 weeks of age [arrow in (F)]. The small and medium size vessels in the subarachnoid space undergo structural changes showing wall thickening in SHRSP. These vessels appear normal at 7 weeks of age [arrow in (G)] while they develop mild thickening at 16 weeks of age [arrow in (H)] and lipohyalinosis at 24 weeks of age [arrow in (I)]. The penetrating small vessels undergo similar changes as well with age (J–L). They largely appear normal at 7 weeks of age (J), while mild thickening is seen at 16 weeks of age [arrow in (K)] and lipohyalinosis is seen at 24 weeks of age [arrow in (L)]. Enlargement of the perivascular spaces can be seen as early as 7 weeks [arrows in (J,M)] and they increase in size at 16 weeks [star in (K) and arrow in (N)] and 24 weeks [star in (O)]. Capillaries are often congested (M). Perivascular hemosiderin is another histopathological finding starting at 24 weeks [arrow in (O)].