MENINGEAL CELLS ORGANIZE THE SUPERFICIAL GLIA LIMITANS OF THE CEREBELLUM AND PRODUCE COMPONENTS OF BOTH THE INTERSTITIAL MATRIX AND THE BASEMENT-MEMBRANE

We have investigated the factors controlling both the morphological tr ansformation of glial processes into endfeet and the deposition of ext racellular matrix molecules into the overlying basement membrane by de stroying meningeal cells over the hamster cerebellum by 6-hydroxydopam ine administration on the day of birth. We report that within 24 h of destruction of meningeal cells, the concentrations of fibrillary colla gens types I, III and IV in the glia limitans externa and the associat ed basement membrane molecules laminin, collagen type IV, and fibronec tin are greatly diminished, resulting in the development of focal gaps in the basement membrane. The immunohistochemical integrity of the ba sement membrane is restored within 3 days over those surfaces of the f olial apices where meningeal cells reappear. Likewise, the fibrillary collagens of the associated interstitial matrix are re-established in the same amounts as in controls. However, meningeal cells remain perma nently absent from fissures and all extracellular matrix molecules tes ted disappear from rostral cerebellar folia covered by the anterior me dullary velum. Moreover, the glial endfeet make up the superficial gli a limitans only on folial apices, while they disappear from the fissur al surfaces. In primary cultures, meningeal cells produce the fibrilla ry collagens type I, III, and VI, and the matrix molecules fibronectin and laminin, collagen type IV, nidogen, and heparansulphate proteogly can. These findings indicate that meningeal cells (i) produce molecula r components of both the interstitial matrix and the basement membrane , and (ii) are involved in the morphological transformation of glial f ibres into the endfeet which constitute the superficial glia limitans.