A series of phase-contrast micrographs showing the reaction to
the addition at 0 sec of broth containing 0.1 µg CA/ml. The dark part
of the Spitzenkörper (S) began to retract at 60 sec leaving a bright
spot (arrows) derived from the original central core. The apical dome became
hemispherical and began to grow in a nonpolar manner between 60 and 320
sec The typical longitudinal orientation of the mitochondria (m) was lost
and they began to enter the area vacated by the Spitzenkörper after
60 sec. ANIMATION. Scale bar = 10 µm.