cytoproct

Description:

Drawing of the cytoproct illustrating four views as it changes shape during vacuole defecation. a) A view of the short segment of the closed and inactive cytoproct. Single microtubules extend into the cytosol from the top of the ridge which is distinguished from other ridges by piles of unique fibers. Bundles of microtubules also extend inward from the adjoining basal bodies. b) The microtubules contact the spent vacuole and move the vacuole toward the cell’s surface. Ultimately the microtubules pull the vacuole and ridge apex together where fusion between the vacuole and plasma membrane can occur. c) Following fusion the spent vacuole membrane tubulates and fission results in release of this membrane back into the cell. Tubulation is promoted by actin filaments. d) The ridge will reform when all spent vacuole membrane is retrieved. Published in J. Cell Sci. 14:611-631, 1974. This image is available in Richard Allen's collection.