Histopathology
Kidneys were collected from human apoB Tg. SHR-cp/cp rats, non-Tg. SHR-cp/cp rats, human apoB Tg. SHR-+/+ rats, and non-Tg. SHR-+/+ rats. Then they were fixed in 10 vol% neutral buffered formalin and embedded in paraffin. The sections were stained with hematoxylin and eosin (H&E) and periodic acid-methenamine silver (PAM). Frozen sections of the kidney from apoB Tg. SHR-cp/cp rats and non-Tg. SHR-cp/cp rat kidneys were also stained with Oil Red O. Using light microscopy, the severities of the tubulointerstitial findings such as degeneration/regeneration, mononuclear cell infiltration, and hyaline casts were determined in H&E-stained sections according to the following criteria expressed on an arbitrary scale from 0 to 4 or 3: tubular degeneration/regeneration (0, no tubular degeneration and regeneration; 1, focal lesions; 2, almost 25% of tubules were affectedd; 3, almost 50% of tubules were affected; 4, >80% of tubules were affected), mononuclear cell infiltration (0, no mononuclear cell infiltration; 1, sporadic and focal infiltrations; 2, multifocal infiltrations; 3, more extensive multifocal infiltrations), and hyaline casts (0, no hyaline cast; 1, a few hyaline casts; 2, multiple hyaline casts mainly in the medulla; 3, multiple hyaline casts in the medulla and sporadic hyaline casts in the cortex; 4, numerous hyaline casts). The severity of the glomerulosclerosis was determined in the PAM-stained sections according to the following criteria expressed on an arbitrary scale from 0 to 4: 0, no glomerulosclerosis; 1, sporadic glomerulosclerosis; 2, sporadic glomerulosclerosis, with adhesion to the Bowman’s capsule in some affected glomeruli; 3, sclerosis lesions in almost 50% of glomeruli, with adhesion to the Bowman’s capsule in less than 50% of the affected glomeruli; 4, sclerosis lesions in most glomeruli, with adhesion to the Bowman’s capsule in more than 50% of the affected glomeruli. In addition, lipid accumulation in the glomerulus was evaluated using sections stained with Oil Red O.