Aspect of primordia of M. perniciosa. A. Section of initial primordium stained with Pianeze III. Note the globose form, the distance between the septa and the pigment impregnated within the hyphal cell wall (arrow; bar = 0.1 mm). B. Hand-cut section of a primordium showing the separation between the tissue that will develop the pileus (P) and the rod that will develop the stipe (S) (bar = 0.25 mm). C. Lamella appeared by digestion in areas of pileus (bar = 0.25 mm). D-F. Scanning electron micrograph. D. Differentiated primordium with radial growing hyphae in pileus (bar = 100 μm, on detail bar = 30 μm). E. Densely packed stipe hyphae (bar = 20 μm). F. Clamped hyphae of primordium (bar = 2 μm). G. Primordia extension stage (bar = 1 mm). H. Different primordia in extension stage (bar = 0.5 cm). I. Basidiomata obtained in vitro with exposed lamellae (bar = 1 cm).