An Observation Concerning the Mechanism of Renal Cyst Formation. *

A technique of producing intrarenal obstruction in the rabbit has been described in detail elsewhere.' In brief, it consists of the insertion of a wire through the surface of the kidney into the papilla or low medulla. Cautery current is then applied, producing a localized thermal injury about 2 mm. in diameter around the tip of the wire. The result is obstruction of a wedge of nephrons. The tubular changes after one week consist of tubular dilatation and atrophy.8 Glomeruli are not altered. After two to four months, atrophic tubules predominate, but many dilated tubules lined with flattened epithelium can still be found. In some areas there is dilatation of Bowman's capsule to approximately twice its normal diameter. A modification of this procedure was employed in a group of rabbits in order to produce renal insufficiency. Three burns were placed in the papilla of the left kidney of eight animals. After two to four months the kidneys were removed for histological and bacteriological study and blood samples obtained for the determination of urea nitrogen (BUN).