Histological analysis reveals that selective ETA receptor antagonism preserves glomerular morphology and prevents vascular congestion in humanized sickle cell mice. Histologic examination of the renal cortex of genetic control (HbAA) and humanized sickle mice (HbSS) treated with vehicle, the selective ETA antagonist, ambrisentan, or the combined ETA/B antagonist, A-182086, for 10 weeks beginning at 4 weeks of age. (A) Depicts representative Masson trichrome–stained sections of glomeruli. Original magnification, ×40 (scale bar=50 μm). (B) Depicts quantification of (A) represented as sclerosis index score. (C) Depicts glomerulomegaly represented as mean area of glomeruli (square micrometer). (D) Depicts number of glomeruli per square millimeter. (E) Depicts representative hematoxylin and eosin–stained sections of glomeruli. Original magnification, ×40 (scale bar=50 μm). (F) Depicts glomerular congestion represented as percentage of glomeruli with congestion. (G) Depicts basement membrane of Bowman’s capsule thickening score. Data are mean±SEM; n=5 in HbAA and HbSS groups; *P<0.05 versus vehicle-treated HbAA; #P<0.05 versus vehicle-treated HbSS. All of the glomerular characteristics were counted in ten sections per slide (minimum 20 glomeruli).