Effect of low temperature on the axons of chick embryo in in vitro culture

Hanging drop cultures of rhombencephalon of 6-11 day chick embryos were placed for 15'-24 hours at low temperatures (0 degree, 10 degrees, 15 degrees, 20 degrees, 25 degrees). Phase contrast time-lapse cinemicrography were made of the axons outgrowth from the explants, during recovery of normal temperature (38 degrees). A number of cultures were also filmed during cooling from 38 degrees to 15 degrees or 20 degrees. It was thus possible follow the sequence of the axon changes, especially of its growth cone, and demonstrate the reversible nature of the modifications observed at some subnormal temperatures.