Ontogeny of cyclic nucleotides in embryonic chick gonads

The cyclic nucleotides AMP and GMP show characteristic patterns of concentration throughout development in the gonads of the embryonic chick. In the ovary, cyclic AMP concentration varies depending upon whether the ovary is regressing (right) or developing (left). In the regressing right ovary cyclic AMP concentration is 4.25 pmol/10(6) cells on day 8 and 1.3 pmol/10(6) cells on day 15 of embryonic development. In the developing left ovary cyclic AMP is approximately one-half that of the right ovary and also decreases throughout this period (2.9 pmol/10(6) cells on day 8 and 0.75 pmol/10(6) cells on day 12 through hatching). Cyclic GMP levels, on the other hand, are similar in right and left ovaries on day 10 (4 and 5 fmol/10(6) cells, respectively). On day 12, however, cyclic GMP in the regressing right ovary increases 5.5-fold while that in the developing left ovary remains constant. In the testis, cyclic AMP and cyclic GMP remain at 0.9 pmol and 6 fmol per 10(6) cells, respectively, throughout embryonic development. Micromolar concentrations of cyclic AMP and cyclic GMP reciprocally inhibit the hydrolysis of each other to a similar degree in the developing left ovary and testis. In the regressing right ovary, however, the hydrolysis of cyclic GMP is not affected by cyclic AMP.