English: EGTA blocks calcium rescue of hd− early development. Dictyostelium hd− cells do not exhibit pulsatile cAMP signaling or chemotactic streaming into aggregation territories when incubated with 1 mM CaCl2 in the presence of 1 mM EGTA. Hd− cells failed to initiate pulsatile waves and consequently do not stream into aggregation centers, become rounded and can be seen randomly colliding. Cells were imaged using brightfield microscopy and images were captured every 15 seconds over a period of 8 hours. Video is representative of the time between 5 and 6 hours with a frame rate of 50 msec.