Changes in insulin and transferrin requirements of pure brain neuronal cultures during embryonic development.

A pure neuronal culture grown in a defined serum-free environment has been developed and characterized. Insulin was the only hormone found to enhance the growth of neurons obtained from embryonic chicken brains during the early proliferative stage, a time when many neurons survived without the addition of any growth factors to the culture. With increasing embryonic age, there was an increase in the number of neurons requiring transferrin. By the time neurons reached a postmitotic state in older brains, they were completely dependent on both insulin and transferrin for survival and growth. Because this culture is free of glial cells and serum, it provides an effective basis for investigating molecular mechanisms underlying neuronal development.