Phase contrast images of growing hyphal tip of R. solani photographed at 30 sec intervals to show the typical apical organization. The Spitzenkörper (s) is composed of two distinct regions, an inner bright core and an outer dark zone. Note the apparent changes in shape of the bright core from frame to frame. Lipid bodies or spherosomes (sp), the very dark round objects, are prominent in the subapical cytoplasm. Mitochondria (m), the medium dark filamentous structures, are found in a compact cluster immediately behind the Spitzenkörper and throughout the subapical cytoplasm. Mitochondria are typically oriented parallel to the long axis of the growing hypha. Small bright components are also scattered in the cytoplasm and on occasion seem to coalesce with each other or with the subapical periphery of the Spitzenkörper core (60 sec view). Animation. Scale bar = 10 µm.