[Electron microscopic study of the mitochondria in the apical meristem of a wheet shoot in ontogeny]

The mitochondria of apical meristem cells in the wheat (Triticum aestivum L.) shoot were studied during ontogenesis using electron microscope and morphometrical methods. Changes in their structure were followed from the juvenile mitochondria of the seed embryonic ear cells. The parameters of the "average" mitochondrion, such as profile area, outer membrane length, were shown to differ relatively weakly during the periods with different meristem activity. Changes in the internal structure of the mitochondria having the developed system of crystae in the actively growing apices and those with weakly developed crystae in the resting seed or low active "waiting meristem" are much more pronounced. The relative volume of mitochondria, their number per unit of cytoplasm volume and total length of membranes suffer relatively insignificant changes during the vegetative phase and increase markedly during the prefloral phase when the apex is preparing itself for generative differentiation.