Perfusion--fixation of human kidneys for ultrastructural analysis

Surgically removed human kidneys were fixed by vascular perfusion to improve the preservation of renal tissue and, in particular, the proximal tubules for electron microscopic analysis. Fifty kidneys with various pathologic changes were perfusion-fixed with glutaraldehyde under pressure control immediately after nephrectomy. A Tyrode solution containing a spasmolytic drug initiated the perfusion. The results demonstrate that large volumes of ultrastructurally well-preserved kidney tissue can be obtained in normal (nontumorous) parts of tumor kidneys as well as in kidneys with chronic nephropathy. Several factors improved the quality of fixation: (1) start of perfusion-fixation within 15 min after clamping of the renal vessels, (2) careful handling of the kidney during nephrectomy, (3) simultaneous clamping of the main renal vessels, and (4) employment of a spasmolytic drug. In comparison with tissue from immersion-fixed renal biopsies, perfusion-fixed kidneys represented an improved basis for ultrastructural investigations of normal or pathologically changed human kidney tissue.