Origin, development, and maturation of organelles and organelle systems of the cell surface in Paramecium

Abstract

At precisely controlled stages throughout their division cycle, single cells ( Paramecium bursaria ) were fixed, embedded, and serially sectioned for electron microscopy. Extensive quantitative and pictorial data constitute evidence for the developmental origin of the principal organelles (cilia, ciliary corpuscles, and trichocysts) and organelle systems (pellicle system, gullet system) of the cell surface. New organelles arise from preorganelles in an orderly sequence of changes closely correlated with nuclear events, and independently of division, bipartition, or budding of corresponding preexisting organelles or organelle systems. The quantitative relationships between the stage of the cell cycle and the numbers and kinds of preorganelles present in the cytoplasm are established, and the ultrastructural consequences of thermal blockade of cell division are described.