Immunocytochemical demonstration of laminin in the synovial lining layer of the rat temporomandibular joint

This immunocytochemical study describes the distribution of laminin in the synovial lining of the rat temporomandibular joint. Laminin immunostaining was present around some synovial lining cells and blood vessels. Ultrastruc turally, immunoreactive products for laminin were deposited around cells wi th a well-developed rough endoplasmic reticulum and secretory granules, sug gesting that they were type B synovial lining cells. The localization of la minin immunoreactivity was not uniform around the cell membrane, the most i ntense immunoreaction being present on the basal aspect membrane as is seen in the basement membrane of epithelia. In contrast, macrophage-like synovi al lining type A cells did not show laminin immunoreactivity. This differen t immunostaining pattern suggests that laminin acts as an adhesion molecule for the type B cells in their epitheliallike arrangement. (C) 1999 Elsevie r Science Ltd. All rights reserved.