INTERCELLULAR MOVEMENT OF PROTOPLASM INVIVO IN DEVELOPING ENDOSPERM OF WHEAT CARYOPSES

Earlier work in our laboratory indicated that protoplasmic constituents can migrate from one cell to another in certain tissues of higher plants. Further investigations have been conducted using garlic bulbs and wheat nucellus for microscopic observation of intercellular protoplasmic movement in vivo. These gave preliminary indications of the dynamic characteristics of migrating nuclei and cytoplasm. The present paper gives recent results providing new evidence for intercellular protoplasmic movement that is neither hindered by the presence of cell wall nor the narrowness of channels of intercellular connection. By careful manipulation, intact endosperm sacs could be taken from developing caryopses (6-8 days after fertilization) without apparent injury to constituent cells. Shortly after the living specimen is mounted on the microscopic stage, asynchronous intercellular protoplasmic movement can be observed here and there. It can be seen that protoplasm extrudes in rapid but intermittent movements from one cell to the next by vigorous contraction. Although various cell constituents may move together, they can also be quite independent of each other. The moving units, though undergoing violent deformation, resume their normal shape and structure following intercellular migration. Evidently this kind of movement is a naturally occurring and active phenomenon closely related to the physiological state of the tissue. Electron microscopic studies reveal that a limited number of plasmodesmatal channels undergo modification and enlarge to 100-400 nm, through which the protoplasmic constituents pass. © 1990 Springer-Verlag.