akinete and heterocytes

Description:

The specialized cells of Aphanizomenon ovalisporum: an akinete (large, thick-walled, egg-shaped cell in the upper filament) and a hetetocyte (egg-shaped, transparent cells in the middle and bottom filaments).   The akinetes are much larger than regular cells and can be mid-filament or terminal, at times a few in a single filament, sometimes several in a row. Akinetes function as asexual resting stage and are resistant to harsh conditions. Akinete formation is induced by P-limitation. The akinetes separate from the filament and sink to the sediments, where they remain until conditions are suitable for germination.