Immunohistochemical analysis was required to identity lymphoid cell subtypes in mouse appendage joint synovium tissue. Hamster and rat monoclonal antibodies directed toward lymphoid cell subtypes were found to be nonreactive in formalin-fixed decalcified appendages, and this necessitated the use of cryostat sections for immunohistochemical procedures. Initial attempts to section mouse joints using conventional cryostat techniques did not yield adequate sections, and it was clear that a different approach was necessary.