[Structure and cell division of the blue-green alga Plectonema boryanum].

Our data on the structure of the blue-green alga Plectonema boryanum, as well as the analysis of the data of other authors, show that its cells resemble bacterial cells in the basic features of their fine structure (the cell wall, cytoplasmic membrane, nucleoid, membraneous formations, ribosomal apparatus). Besides the organelles typical of blue-green algae, organelles similar to mesosomes and formations looking like lysosomes were found in Pl. boryanum. Data obtained in the course of the formation of cell partitions evidently speak in favour of the many-sided activity of the lamellae of the photosynthetic apparatus (the parachromatophore) of Pl. boryanum.