Histochemical demonstration of carbonic anhydrase activity in the amnioallantois and chorloallantois of the developing chicken embryo

The carbonic anhydrase activity in the amnioallantois and chorioallantois of developing chicken embryos was studied using the histochemical technique of Hannson (1967). Tissue samples were taken from chicken embryos on days 8, 10, 12, 14, 16 and 18 of incubation. Enzyme activity was demonstrated in the chorionic epithelium, in endothelial cells (lining blood vessels in the allantoic mesoderm), and in the allantoic epithelium of the chorioallantois. In the amnioallantois, enzyme activity was found in the amnionic epithelium, endothelial cells (of the allantoic mesoderm), and allantoic epithelium. A distinct staining pattern was present in each membrane and the level of carbonic anhydrase activity increased throughout the incubation period studied. In the control sections 10⁻⁶ M acetazolamide (a specific carbonic anhydrase inhibitor) inhibited staining.