Electron microscopy study of cell structures and their changes during growth and regeneration of Schizosaccharomyces pombe protoplasts.

Abstract

The submicroscopic structure of growing and regeneratingSchizosaccharomyces pombe protoplasts cultivated in solid and liquid medium was studied by means of ultrathin sectioning. The protoplasts regenerate within 24 hours. Shortly before growth commences, rudiments of the new cell wall can be identified on the protoplast surface. Simultaneously, a large number of dictyosomes appears in the cytoplasm and decreases as synthesis of the new wall progresses. An increase occurs in the number of endoplasmic reticulum membranes some of which are arranged parallel with the cytoplasm membrane of the protoplast. Throughout the whole time of regeneration the protoplasts contain only one nucleus. The nucleo-cytoplasm ratio of growing and regenerating protoplasts is lower than in intact cells. The number of mitochondria falls at the outset of regeneration and does not rise again until towards the end.