The present work includes anatomical and histological study of the kidney of guinea pig. The current study was performed on (10) kidneys from (5) mature (male and female) gene pig clinically healthy. The animals were anaesthetized by the ether after which they were carefully dissected and examined. The anatomic studies showed the urinary system of guinea pig was composed of two kidneys. The kidneys are retroperitoneal organs bean in shape, red pink in colure and situated in the posterior part of the abdomen on each side of the vertebral column. The mean weight of right and left kidney (0.205±1.998) mm. The mean length, width and thickness of right kidney (20.356± 0.850) mm, (14.396±830) mm, (8.198±0.450) mm respectively .While the mean length, width and thickness of left kidney (18.296±0.722) mm, (13.776±0.939) mm, (8.192±0.440) mm respectively. The cross section of kidney showed two anatomical distinct regions, the outer cortex and inner medulla, both terminate by renal papilla. The renal cortex is reddish brown in colour. The mean width of cortex and medulla of right kidney (5.554±0.371) mm, (5.508±0.180) mm respectively while the mean width of cortex and medulla of left kidney (5.780±1.792) mm, (5.492±0.205) mm respectively. The result of histologic study demonstrate the kidney consist of outer dark red region (cortex) and inner lighter colored region (medulla) there is no evident boundary between the cortex and medulla . The renal corpuscle (malpighian) is a spherical structure formed of glomerulus, which is enclosed by a double-walled Bowman’s capsule. Proximal convoluted thin tubules carctrestic by have widest lumen and internally lining by cuboidal epithelial cells which resting on the basement membrane. This cells characterized by have ground eosinophilic cytoplasm, large centrally nuclei and the apical surface covered by a brush border called microvilli. While the epithelial lining of distal convoluted tubules have extensive lumen and cuboidal cells have ground cytoplasm was clearly less eosinophilic than that of the proximal tubules and the apical surface of the distal convoluted tubule was uncovered by short microvilli.
