Studies on Submicroscopic Structures of Bacterial Cells I. Electron Microscopy of Ultra-thin Sections of Bacillus Aneurinolytic Us1

In recent years, much evidence has been obtained on the submicroscopic structure of bacterial cells. However, still much work remains to be done before one can have a clear picture of bacterial cytology. If further advances are to be expected in this field of study, some of the most fundamental problems of the bacterial nucleus should be clarified, namely what is the real nature of the nucleus, is it surounded by a membrane and is it made up of chromosomes? The results obtained by differential staining and light microscopy(DeLamater and Hunter, 1952; Robinow, 1953a; Knaysi, 1955) provided an approach to the problem. Following these reports, several works have been carried out, applying the techniques of ultramicrotomy accompanied with electron microscopy (Chapman and Hillier, 1953; Brich-Andersen et al 1953; Robinow, 1953b; Bradfield, 1954; Higashi, 1955; Chapman, 1956). In spite of these investigations, the problem of bacterial nuclei still needs further clarification. In a preliminary report Ito and Ozaki (1957), observed a fine internal structure in the nucleus of Bacillus aneurinolyticus, which reminded the authors of the nuclear reticulum of higher organisms. The present study was undertaken to gain further information, especially on the internal structure of the nuclear apparatus of B. aneurinolyticus, and its behavior during the process of sporulation.