The lack of metastatic behaviour of primary glioma is poorly understoo
d. A possible natural barrier accounting for this phenomenon may be th
e proteins of the extracellular matrix which are found in the basement
membranes of the blood vascular system. This hypothesis is reinforced
by the finding that glioma invasion in vitro using a syngeneic model
system results in a lack of invasion areas of target tissue which cont
ain extracellular matrix proteins. The study was extended by examining
the effect of the incorporation of these proteins during the formatio
n of fetal rat brain cell aggregates and glioma spheroids and on the i
nvasion of aggregates by tumour spheroids. Laminin was shown to reduce
the size of the aggregates and spheroids during their formation while
fibronectin and type IV collagen had no effect. Laminin also prevente
d the invasion of the tumour spheroid into the target aggregate and ap
peared to inhibit migration of glioma cells on laminin coated tissue c
ulture plastic.