Electron microscope studies on the vegetative cellular life cycle of Chlamydomonas reinhardi Dangeard in synchronous culture I. Some characteristics of changes in subcellular structures during the cell cycle, especially in formation of giant mitochondria1

Abstract

Changes in subcellular structures during the entire vegetative cell cycle of Chlamydomonas reinhardi Dangeard in synchronous culture were followed with an electron microscope. Giant mitochondria of various shapes were temporarily formed, probably by fusion of smaller mitochondria, in the algal cells at an intermediate stage of the growth phase of the cell cycle. Formation of giant mitochondria was accompanied by a marked decrease in the oxygen-uptake activity of cells. Giant mitochondria divided into smaller forms concurrently with a re-increase in the oxygen-uptake activity of cells. Some characteristics of changes in the structures of chloroplast, the nucleus, the endoplasmic reticula, flagella and dictyosomes are described.