Monocyte escape through a glomerular capillary basement membrane gap. An ultrastructural observation in a case of acute glomerulonephritis.

A focal discontinuity of glomerular basement membrane (GBM) with extravasation of a monocyte is described in a case of acute postinfectious glomerulonephritis in a 2-year-old girl. It is proposed that also monocytes could play a role in causing disruption of glomerular capillary wall. Moreover, this finding gives morphologic support to the hypothesis that monocyte-forming crescents reach the urinary space through GBM gaps.