Ultrastructural Changes of the Uriniferous Tubules after Ureteral Ligation in Rabbits

Yoon, Ki Hun; Lim, Su Kil

Abstract

This study attempted to clarify the morphological changes of the uriniferous tubules in the postobstructed kidneys of rabbits by electron microscopy. A total of l3 rabbits weighing about 2.5 kg were used. Under penthothal sodium anesthesia, complete ureteral obstruction was accomplished by ligation on the left ureter 1 cm above the ureterovesical junction. The experimental animals were sacrificed at the second and fourth week after the unilateral ureteral ligation. Tissue specimens taken from the renal cortex and medulla were fixed in a mixture of 2% paraform-aldehyde-2.5% glutaraldehyde (phosphate buffer, pH 7.2 ) prior to fixation in 1% osmium tetroxide (phosphate buffer, pH 7.2), and embedded in Epon 8l2. The sections were cut with LKB-III ultratome. Ultra thin sections were contrasted with uranyl acetate and lead citrate, and examine with a JEM-100B electron microscope. The results were as follows: 1. In the 2 weeks group of postobstruction, the abnormal morphology of the uriniferous tubules was: diminution in microvilli and basal invaginations, widening of intercellular space, focal necrosis of the epithelium, desquamation of tubular cells and splitting of the basal lamina. The degenerative changes were severe in the distal tubule, loop of Henle and collecting duct. However, the changes were mild in the proximal tubules. 2. In the 4 weeks group of postobstruction, the degenerative changes were more severe and generalized in all portions of the uriniferous tubules, and focal necrosis and desquamation of the epithelial cells were prominent in the distal tubules and collecting ducts. 3. In both groups of postobstruction, the epithelial cells with mild deformity, such as a decrease of microvilli and basal invaginations, were still preserved in all portions of the uriniferous tubules. From these findings in the obstruct nephropathy, degenerative changes are progressively expedited and partially produced in the urinary tubules.