Heterocysts in Cyanobacteria – Definition, Structure, and Function Explained
Heterocysts are specialized nitrogen-fixing cells formed by some filamentous cyanobacteria such as Nostoc, Anabaena, and Cylindrospermum when nitrogen is scarce. They contain the enzyme nitrogenase, which converts atmospheric nitrogen (N₂) into usable forms for other cells. To protect nitrogenase from oxygen, heterocysts develop thickened walls and create a low-oxygen internal environment.
