Fig. 5. Fibulin-1 inhibits the invasion of endocardial cushion mesenchymal cells into gels of type I collagen and fibronectin. Stage 18 chick endocardial cushion explants were placed onto the surface of gels of type I collagen (1 mg ml^–1) containing FN (20 µg ml^–1) plus or minus fibulin-1 (100 µg ml^–1). The number of cells that had invaded into the gels (A) and the depth of invasion (B) were quantified after 50 hours. The plotted values in A are means ± the standard deviations from measurements made on four cushion explants. (A,B) The number of cells in optical planes extending through a depth of 400 µm of the gel in four areas underlying each explant was counted and summed. Asterisk (*) indicates that the value is significantly different from control (P<0.05).