The aim of this study was to explore the developmental character of neurons from dorsal root ganglion (DRG) of embryonic chicken in vitro. The DRG neurons of Hamburger stage 35 were cultured and prepared at 0, 1, 2, 3, 4, 5, 7, 14 and 21 days respectively. The number of neuronal survival was counted at each cultured stage (observed area: 2.5 x 10(5) microns 2) and the morphological change of neurons in vitro was observed and compared with that of neurons in vivo. The results showed the counts of neuronal survival were 94 +/- 4, 83 +/- 6, 67 +/- 4, 65 +/- 7, 68 +/- 5, 71 +/- 9, 73 +/- 6, 22 +/- 4, and 0 respectively; the cultured neuronal shape during 48 h incubation was mainly oval or sphere, similar to that of neurons in vivo. However, the shape of some neurons changed into cone or shuttle after three days incubation, while the neuronal shape in vivo did not change. These findings indicate that only some of neurons can survive and grow and the lifetime is limited in vitro, on the other hand, the developmental character of neurons in vitro may be different from that of neurons in vivo.