Ultrastructure and Differentiation in Chara Sp.I. Vegetative Cells

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Abstract
The ultrastructure of young growing cells of Chara is described. The cells showed many features typical of plant cells. The nuclei of larger cells invariably contained groups of close-packed, heavily staining microtubular elements. Typical wall microtubules were always found, and large internodal cells contained filaments possibly involved in cytoplasmic streaming. Vacuolation in young internodes apparently commenced by extensive dilation of elements of the endoplasmic reticulum. In other cells, close apposition of endoplasmic reticulum to cytoplasmic inclusions indicated possible secretion of material into the organelles had been occurring. Golgi bodies with intereisternal elements were often grouped together, sometimes with interconnected cisternae. Isolated reticulate membrane systems, similar to those found at the reticulate face of golgi bodies, were sometimes seen in vacuolated cells. The golgi bodies might have been involved in vacuolation; they were also seen in association with coated vesicles that appeared to be involved in wall deposition. A large number of different cytoplasmic inclusions were found, whose nature and function is obscure. These sometimes contained crystal-like bodies. The results are discussed in terms of the possible functions of the organelles, particularly with respect to morphogenesis and the patterns of cells formed during growth.