Ultrastructural localization of adenylate cyclase and cAMP phosphodiesterase in the gastrulating chick embryo.

The ultrastructural localization of adenylate cyclase (E.C. 4.6.1.1.) and cAMP phosphodiesterase (PDE) (E.C. 3.1.4.17.) in the ectoderm of the developmental stage 4 chick embryo was studied. Adenylate cyclase was localized in the lateral surfaces of the ectodermal cells. In the primitive streak cells the enzymatic activity was observed on all the lateral surfaces, whereas in the periphery of the blastoderm the reaction product was localized in the apical parts of the lateral plasma membranes only.cAMP PDE localized in the apical cytoplasm of the ectodermal cells, with highest activity in the globular projections.