[Ultrastructural findings in the so-called minimal glomerular changes].

Fifty-eight needle biopsies of the kidneys with the light microscopical diagnosis of so-called minimal glomerular lesions were subjected to ultrastructural evaluation. The series contained children and adults under 25 years of age with the mean age of 16.9 years. The most frequent findings were those of the glomerular epithelia: vacuolation and swelling of their cytoplasm in 72.8%, microvilloustransformation in 13.6%. Endothelial lesions were less frequent: swelling and vacuolation of their cytoplasm occurred in 46.6%. The most important ultrastructural lesions appeared to be the mesangial ones. Focal increase in the mesangial matrix was seen in 44.8% and small intralobular scars in 13.6%. True focal increase in mesangial cells was rare (6.9%). The formation of duplicatures of the basement membranes in the glomeruli was exceptional (3.6%). Another important ultrastructural finding was a focal thickening of the basement membrane in a larger number of cases (32.3%). Deposits were found rarely (7 cases, 12.1%) most of them occurring in the mesangium. The cellularity of the glomeruli did not exceed the normal range.