| Abstract: | Wall materials are deposited in giant culture cells of Nicotiana tabacum L. by specialized vesicles. Vesicles arising from localized hypertrophy of the endoplasmic reticulum are filled with carbohydrate precursors by means of smaller vesicles originating from the golgi apparatus. Once inside the larger vesicle, the golgi microvesicles swell and lose their contents due to osmotic forces. The carbohydrate is then polymerized into microfibrils within the larger vesicle that is hereafter termed the "cellulose depositing vesicle" (CDV). Upon union and externalization of the CDV with the plasmalemma, the vesicles, remaining inflated, are dragged along the inner face of the secondary wall by cytoplasmic streaming and deposit their contents on the inner surface of the wall. Small vesicular-like structures, resembling or identical to the lomasomes, are formed by folds that appear in the membrane as the empty CDV collapses and becomes incorporated into the plasmalemma. ... |
|---|