Cyclic nucleotide content of ciliary and dorsal root ganglia during embryonic development in the chick

The concentration of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) was measured in developing chick ciliary (CG) and dorsal root ganglia (DRG) as a function of embryonic age from day 8 through day 18 using radioimmunoassays. The concentration of cAMP and cGMP increased in both ganglia from day 8 through day 14. cAMP levels were nearly two-fold higher in DRG than in CG. Normalization of the data for ciliary ganglia to the number of cells per ganglion and calculation of their molar concentrations indicates a 48% increase in cGMP and a 3.2-fold increase in cAMP during the developmental process of natural neuronal cell death.