[Effect of preincubation irradiation on adenylate cyclase activity and cyclic nucleotide content of the thymus in chick ontogenesis].

Adenylate cyclase activity and cAMP and cGMP content of thymus have been studied in intact and irradiated (0.029 Gy, prior to incubation) embryos and chickens. The enzyme activity is stimulated during the postnatal development. The changes in the cyclic nucleotide content are undulatory and oppositely directed. It is suggested that the observed radiation-induced stimulation of adenylate cyclase and the reciprocal changes in the cyclic nucleotide content after hatching are related to the increased specific differentiation of thymus cells.