Ultrastructural correlates of anaerobic stress in corn roots.

Cytological events in Zea mays root meristem were followed during 26 hr of anaerobic treatment. From 8 to 14 hr, mitochondria swelled drastically, Golgi apparatus actively produced vesicles, endoplasmic reticulum proliferated, and chromatin strongly condensed. Plastids appeared normal. By 26 hr, however, Golgi activity receded, mitochondria assumed long, polymorphic shapes, chromatin partly dispersed, and plastids swelled. ER remained prominent, and the cytoplasm contained long fibrous inclusions. This preliminary study emphasizes the need to examine quantitatively all cellular organelles periodically for longer periods when following events of stress or pathology. Our observations corroborate scattered reports in the literature for single organelles under anaerobic stress and represent the first set of correlated observations on the entire spectrum of cellular events.