Fig. 7. Schematic diagram showing developmental changes in the synthesis of GDNF, NRTN and CNTF proteins in the chick embryonic eye. The darkest area indicates the highest protein level. The data on GDNF and NRTN are from the present study, whereas the data on CNTF are from Leung et al. (Leung et al., 1992) and Finn and Nishi (Finn and Nishi, 1996).