LR-White and LR-Gold resins for postembedding immunofluorescence staining of laminin in mouse kidney

This work describes a method for the immunolocalization of laminin on 1 micron-thick tissue sections using a postembedding immunofluorescence technique. Embedding of unfixed or formaldehyde-fixed mouse renal cortex in either of the acrylic resins LR-White or LR-Gold permitted reliable postembedding immunofluorescence staining for laminin. LR-White was heat-cured at 50 degrees C whereas LR-Gold was polymerized at -25 degrees C. A stronger immunostaining for laminin was obtained from tissue embedded in polymerized LR-Gold compared with the staining from tissue embedded in LR-White. Prerequisites for adequate postembedding immunostaining are the partial dehydration of the tissue (maximum ethanol concentration, 70%) and pepsin treatment of the tissue sections prior to performing the immunostaining reactions.