The cytopharyngeal basket in Nassula consists largely of microtubules. During binary fission the old basket is resorbed and simultaneously two new baskets develop. Changes in basket structure occurring during basket development and resorption, and variations in the lengths of baskets during the interfission period have been examined using phase-contrast and electron microscopy. These examinations indicate the manner m which several different processes influence the shapes, sizes, positions, and numbers of the various basket components.
Early in development some of the microtubular basket components contact certain basal bodies from which they subsequently detach, and then, while most of them assemble into the positions they occupy in the mature organelle, they are temporarily associated with a reticulum of microtubules. Several of these components are not included in a new basket and some of them are resorbed; development of the others continues and they establish microtubular connexions to basal bodies different from those to which they were previously attached. Other basket components commence development after assembly of the microtubular components and form in contact with them, even if they have not been included in a new basket. The majority of microtubules apparently lengthen by accumulating material exclusively at one of their extremities Baskets of starving organisms gradually shorten by loss of material from their bottoms but lengthen again when the organisms feed The bulk of an old basket is not enclosed in a vacuole when it is resorbed; breakdown of tubules progresses from their extremities after loss of intertubular cross-connexions
- Received May 30, 1969.
- Copyright © 1970 The Company of Biologists Ltd.