Ultrastructural Study on the Renal Corpuscle after Removal of Ureteral Obstruction in Rabbit

Kim, Tae Kyung; Lim, Su Kil

Abstract

This study was designed to clarify morphological changes in the renal corpuscles of the experimental rabbit kidney after unilateral ureteral obstruction and release of Unilateral ureteral obstruction through a light and electro microscopy. It was further aimed at obtaining data, esp. of electron microscopy, concerning the morphological repair after relieving ureteral obstruction. A total of 25 white rabbits, weighing 2.5kg, were used. 25 rabbits were divided into three groups-normal control, unilateral ureteral obstruction, release of unilateral obstruction. The normal! control group consisted of 5 rabbits. The remaining 20 rabbits were completely ligated in the left ureter with silk threads. Ten obstructed kidneys were studied by light and electron microscopy, five of them two weeks after obstruction, and the remaining five four weeks after obstruction. A total of ten postobstructed kidneys, five of which were reoperated by Mackinnon method for the relief of ureteral obstruction two weeks after obstruction and the remaining five four weeks after obstruction. They were studied for light and electron microscopy 15 days after relieving ureteral obstruction. Specimens of renal cortex from experimental animals were fixed in 10% neutral formalin or Bouin's solution, embedded in paraffin wax, sectioned at a thickness of 5 um, and stained with hematoxylin-eosin, periodic acid-schiff reaction or Masson's trichome for light microscopy. For electron microscopy, the tissues were fixed in a mixture of 2% paraformaldehyde and 2.5ao glutaraldehyde (phosphate buffer, pH 7.2) prior to fixation in 1% osmium tetroxide (phosphate buffer, pH 7.2) and then embedded in Epon 812. The sections were cut with LKB- III ultramicrotome and contrasted with uranyl acetate and lead citrate and examined with electron microscopy JEM 100B. The results of this study were as follows: 1. The abnormal morphology of the glomerulus in kidneys obstructed for four weeks showed: Slight glomerular congestion, capillary dilatation, no changes in endothelium, podocyte and microstructures. 2. Deformity of Bowman's capsular epithelium such as irregular basal invaginations facing with the basal lamina was observed in the two week obstructed kidneys, and severe degenerative changes such as desquamated capsular epithelial cells in the Bowman's space and long basal cytoplasmic processes embedded in the basal lamina in the four week obstructed kidneys. 3. Among the postobstructed kidney, the two week obstructed kidneys were restored to near normal on the 15th day, but in the four week obstructed kidney, Bowman's capsular epithelium showed partial recovery. 4. The results indicate that glomeruli in the renal corpuscle were preserved until four week weeks after ureteral obstruction but Bowman's epithelium showed change in the 2nd week after obstruction and severe degenerative changes of Bowman's capsular epithelium were noticed in the 4th week after ureteral obstruction. The morphological changes were totally restored in the group where ureteral obstruction was relieved after two weeks, but in the group which was relieved of ureteral obstruction after four weeks the morphological repairs were prolonged until after 15 days.