Abstract
Vesicle-like structures containing several to numerous concentric membranes, called multilamellar bodies (MLBs), are present both in animal and plant cells. The origin of MLBs in animal cells has been elucidated partially, while that of plant MLBs is unknown. MLBs in plant cells are present in the cytoplasm, at the interface of cytoplasm and vacuole, and inside vacuoles. This suggests that they become transported from the cytoplasm to the vacuole. The function of plant MLBs thus seems transfer of cellular membranes to the vacuole. Although it is often impossible to discern whether they have a single or a double outer membrane, in some examples a double outer membrane is present. This might suggest autophagic/mitochondrial/plastidial origin. Membrane structures similar to those in MLBs have not been described, apparently, in mitochondria. By contrast, structures similar to MLBs are found in autophagous structures and in degenerating chloroplasts and other plastids. The data might suggest the hypothesis that plant MLBs derive from autophagous structures and/or from plastids.
