Morphogenetic Events in Normal and Synchronously Dividing Tetrahymena
Synchronous cell-division has been induced in mass cultures of the small ciliated protozoan Tetrahymena pyriformis (Scherbaum & Zeuthen, 1954). While it is known that cells grow in a characteristic way during the synchronizing treatment the effect on the morphogenetic events associated with the cell cycle is not clear. Studies in ciliate morphogenesis generally have established the central position of the ciliary basal body, or kinetosome, in developmental processes. The kinetosomes are believed to be self-duplicating structures, the kinetosomal population of a daughter cell arising directly by kinetosomal reproduction in the parent cell. The species-specific pattern of the ectoplasmic cortex is largely a matter of the distribution of kinetosomes. Further, the kinetosomes appear to function either as building blocks or ‘local organizers’ in most, if not all, structural syntheses occurring in the cortex, i.e. in the production cilia, cirri, membranelles, trichocysts, and other ciliate structures (see Weisz, 1954).