Movie 1

Time lapse movie of sox1a:eGFP transgenic embryo from 20 hpf to about 36 hpf in lateral view of the spinal cord. Sox1a:eGFP+ V2 neurons initiate GFP expression in the intermediate region of the spinal cord and send their axons downwards to the tail. Ventrally located cells are KA neurons. Note that the sox1a:eGFP expressing cells never divided. We thus believe that GFP accumulation relative to mRNA accumulation is delayed in the transgene precluding the observation of very early events during and immediately after birth of the neuron.