Hypoelectrolytic isoosmotic solution for infusion prevents saline-induced ultrastuructural artifacts of renal biopsy specimens.

Artifacts in the process of specimen preparation are frequent in ultrastructural evaluation of renal biopsy. We hypothesized that the common practice of wrapping kidney biopsy specimens in saline-soaked gauze to prevent the drying of the specimens could be the major factor of artifacts. In this study, whole kidneys from two male Sprague-Dawley rats were used. Before fixation, fresh small cubes of kidney tissue were macerated in saline (Saline group) or hypoelectrolytic isoosmotic solution for infusion (HISI group) (Sorita T3 or SOLDEM 3A) for 10 or 30min. Then, the specimens were processed by 1% OsO4 in 0.1M phosphate buffer (pH7.4) and embedded by EPON 812 for ultramicroscopic analysis. In the Saline group, ultrastructural examination revealed swollen podocyte, swollen capillary protuberance of the mesangium into the glomerular capillary loop, tubular cells with swollen mitochondria and microvilli, and the smooth muscle cells in the arteriolar wall with marked vacuolar degeneration were detected after 10min maceration in saline and these findings become more pronounced after 30min maceration. However, in the HISI group, these artifacts were not identified or limited within 30min. It is postulated that HISI solution could prevent the artifacts, and be used for soaking and wrapping instead of physiologic saline solution.