Silver-enhanced colloidal-gold labelling of rabbit kidney collecting-duct cell surfaces imaged by scanning electron microscopy.

The luminal cell surfaces of rabbit kidney cortical collecting-duct cells were labelled with peanut lectin (PNA) and investigated by scanning electron microscopy. Labelling was performed either on 20-microns-thick cryostat sections from prefixed and cryoprotected rabbit kidney tissue or on cultured collecting-duct epithelium using biotinylated PNA and a 6-nm colloidal-gold-coupled antibody against biotin. Colloidal-gold labels were detected at low magnification (2000-4000x) using silver enhancement. Coating with chromium allowed simultaneous imaging of both cell-surface morphology and labelling topography in the backscattered electron imaging mode. Our results show that PNA binding is specific for a subtype of intercalated cells equipped with microvilli on the luminal surface. The presented method promises to be useful for the identification of specific cell types in heterogeneous tissues.