Ultrastructural observations in two cases of acute pyelonephritis

Abstract

In two histologically diagnosed cases of acute pyelonephritis, several ultrastructural features were observed. The transmission electron microscope (TEM) highlights the bacterial adhesion, inflammatory process, phagocytosis and lysosomal release characteristic of pyelonephritis.The renal biopsies from both patients were fixed in 2.5% glutaraldehyde, rinsed with Millonig's buffer, and post fixed with 1% osmium tetroxide. They were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole's buffer, dehydrated with a graded series of ethanols and embedded with Epon 812 epoxy resin. Ultramicrotomy thin sections were stained with uranyl acetate and lead citrate and scanned using a JEOL - JEM100C.Using the TEM, bacteria are seen in tubular epithelial cells, phagocytized to the basement membrane, within cells of the tubular lumen, and within the polymorphonuclear leukocytes (polys). Bacteria may also be seen phagocytizing within cells in the tubular lumen. The inflammatory response of polys is seen in the tubular lumen and interstitium, and attached and within the tubular basement membrane.