(A) We label retinal ganglion cell growth (RGC) growth cones in live embryos at approximately 30 hours post-fertilization by placing them in a solution of methylcellulose. We then inject the fluorescent, lipophilic dye, DiI, into one eye and allow the dye to diffuse. (B) After a few hours, we embed several embryos in a droplet of agarose made up in embryo medium containing tricaine and image using a laser scanning confocal microscope. (C) A series of optical sections through the growth cone and its trailing axon are imaged every 3 minutes. The z-series at each time point is projected into two dimensions and the resulting images are combined into time-lapse movies such as those seen below. (Thanks to Charles Holly Jr. for writing the java plugin enabling composition of movies.)
The movies (please be patient, these may take some time to load):
A wild-type growth cone migrates across the ventral forebrain.
Two wild-type growth cones exhibiting different behaviors as they migrate across the ventral forebrain.