Cellular dedifferentation and redifferentiation in Splachnum ampullaceum (L.) Hedw
MacNutt, Mary Margaret
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The phenomena of dedifferentiation and rediff-erentiation in Splachnum ampullaceum are discussed. A quantitative study of changes in the size and number of the main cellular constituents as well as changes in their position are investigated in mature leaf cells during dedifferentiation. Cell division, wall formation, and the factors affecting them are considered. The effects of ageing on regeneration are studied by a comparison of apical and basal leaves. The isolation of parts from the whole plant is necessary for the initiation of cellular changes during dedifferentiation. These changes include increases in size and number of the various cell constituents, and cytoplasmic strand formation and systrophe. Systrophe is considered as an important event in cellular dedifferentiation. Isolation causes a loss of polarity, the reestablishment of which is necessary for redifferentiation. It is concluded that wounding does not play an important role in dedifferentiation, but it is responsible, at least, in part for the reestablish-ment of polarity which leads to differential division and redifferentiation.