Immunohistochemical analysis of asialo GM1-positive cells infiltrating and surrounding Matrigel plugs. Paraffin-embedded sections from Matrigel plugs alone or Matrigel plugs impregnated with bFGF, or bFGF + IL-12 were stained with a monoclonal antimouse asialo GM1 antibody, counterstained with hematoxylin, and examined by light microscopy. Original magnification ×40.