Ultrastructural cytochemical localization of adenylate cyclase in the early chick embryo.

Adenylate cyclase activity was localized in various tissues of the early chick embryo using an ultrastructural histochemical technique. Reaction product was deposited on the lateral plasma membrane of all cells, but with a preferential localization at the apical terminal complex in the epiblast. There was no activity associated with the free surfaces of these or other cells in the embryo. Intracellular deposits were found in all cells associated with the endoplasmic reticulum, nuclear envelope and Golgi bodies. In the last organelle, the deposit was sometimes observed to be distributed through the stack in a non-uniform way, with the heaviest deposits occurring at the forming face. No clear difference could be detected between the cytochemical activity associated with cells in various regions of the embryo, or with embryos at different stages of early development.