Vascular pathology.

<p>Cerebral vessels of animals sacrificed 3 hours after SAH. Panel A: representative images of ICA from a single male and a single female rat. Panel B: average vessel sizes. Note that the internal circumference of ICA in SAH males is smaller compared to females. Panel C: representative images showing brain vessels stained for platelets, RECA-1 (an endothelium marker), and collagen-IV (a basal lamina marker); note the greater numbers of RECA-1 and collagen IV stained vessels containing platelet aggregates (arrows) in males. Panel D: average area fractions of RECA-1 and collagen-IV positive vascular profiles of SAH animals as percent changes over sham-operated cohorts. The reduction in the area fraction of RECA-1 is similar in males and females but that of collagen -IV is different. Data are mean ± sem from 5 animals per gender. * significantly difference than females (p <0.01).</p

Cell death.

<p>Activated caspase-3 immunoreactivity and TUNEL staining 3h after SAH. Panels A-B: 4-color fluorescence staining for TUNEL, NeuN, collagen-IV, and DAPI. Panel A: typical micrographs from male and female SAH animals. Each channel is shown as a separate image. Small arrows: TUNEL-positive neurons; large arrowheads: TUNEL-positive vascular cells. Note the greater frequency of TUNEL-positive neurons in male as compared to female. Panel B: average numbers of TUNEL-only, TUNEL+NeuN, and TUNEL+collagen-IV profiles. TUNEL-only and TUNEL-NeuN profiles are significantly greater in males than in females. Panel C: average numbers of profiles positive for activated caspase-3 (Cas) only, Cas+NeuN, and Cas+collagen-IV. All three indexes are significantly greater in male animals. Panel D: Fluoro-Jade B-positive cells (arrows) in representative SAH male and female brain sections. Panel E: Average numbers of Fluoro-Jade B-positive cells in SAH animals. Data are mean ± sem from 5 animals per gender. * significantly gender difference (p <0.05). </p

Cerebral inflammation.

<p>Luminal platelet aggregates and neutrophil accumulation in animals sacrificed 3 hours after SAH. Panel A: representative images of neutrophil staining. Note the greater number of neutrophils in male as compared to female brain. Scale bar = 500 μm. Panels B, C: average numbers of neutrophils and vascular platelet aggregates per whole brain section and per image field, respectively. Both parameters are greater in male as compared to female brains. Data are mean ± sem from 5 animals per gender. * significantly difference than females (p <0.05).</p

Correlation analysis.

<p>The association of ICP peak values with numbers of platelet aggregates (A), neutrophils (B), and apoptotic cells (C). The ICP peak significantly correlated with the number of apoptotic cells but not with the numbers of platelet aggregates or neutrophils. Each point is the mean from a single animal.</p

Subarachnoid hematoma.

<p>Panel A: representative images of subarachnoid blood in male and female rats at 3 hours after SAH. Subarachnoid clots (outlined in white in the images) exhibit a characteristic granular immunofluorescence for RECA-1 and are both surrounded by and infiltrated by neutrophils. In general, individual clots in males were larger and clots in females were smaller. ON: optic nerve; scale bar = 200 μm Panel B: the summed areas of subarachnoid blood were determined by tracing. The accumulated data show areas larger in males than in females, a trend which did not reach significance (p=0.4). Data are mean ± sem from 5 animals per gender. Cryostat sections from animals sacrificed at 3 hours after SAH and immunofluorescent for RECA-1 and neutrophils (HB-199) were used for this determination. As stated in Methods, the perfusion fixation procedure employed caused subarachnoid blood to adhere to the brain surface during removal of brains from the cranium. The grayscale images combine signals from two color channels.</p