High Resolution Helium Ion Scanning Microscopy of the Rat Kidney
(A) Detail of a glomerular podocyte showing a secondary projection and interdigitating foot processes (GA-fixation, extended methanol freeze-substitution dehydration protocol). Many tubular projections with more bulbous ends (white arrows) emerge from the podocyte membrane. Small (20–30 nm) irregularities of unknown nature can be seen on the external surface of the podocyte membrane (black arrows). Bar = 120 nm. (B) Detail of four “filtration” regions (slit diaphragms) between five adjacent podocyte foot processes. Numerous cross-bridging filaments extend at regular intervals across the space between adjacent foot processes (smaller arrows). In some regions, these delicate structures appear damaged, revealing another structure below, which may represent the glomerular basement membrane (larger arrows). Bar = 100 nm.