Lack of duplication of the number of total volume of mitochondria in the cell cycle of antheridial filaments of Chara vulgaris L.
On the basis of the light and electron microscopic studies of synchronously dividing cells of antheridial filaments in Chara vulgaris, it has been determined that mitochondria maintain their individuality throughout the whole cell cycle. They are mostly round or ovale in profiles, rarely rod-, and occasionally dumbbell-shaped. Synchronisation of mitochondrial cycles does not occur within a single cell: the increase in the number of mitochondria is gradual and continuous, and their average sizes are approximately constant. In all phases of the cell cycle mitochondria occupy about 1.3% of the cell volume. As in the case of the cell volume, neither the total volume nor the number of mitochondria duplicates in the course of interphase, both values reaching merely 2/3 of than characteristic of the previous cycle. Within a single filament, after 4 successive mitotic cycles leading to an 8-fold increase in number of haploid nuclei, the number of mitochondria is only 3 times higher. This phenomenon is connected with morphogenetic reduction of cellular dimensions in successive and gradually shorter mitotic cycles preceding the stage of spermatids. It is supposed that the shortening of the nuclear cycle in consecutive generations of antheridial filaments is not accompanied by a proportional reduction of the mitochondrial cycles.
D002452:Cell Count; D002453:Cell Cycle; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure*; D059828:Plant Cells; D010944:Plants / Q000648:ultrastructure*