[Ultrastructure of L-forms. II. L-forms of Listeria monocytogenes]

A study was made of ultrathin sections of the stable l-forms of listeria obtained under the action of penicillin in meat-peptone-liver broth. A marked cellular polymorphism was found in the L-form culture: within the same colony cells differed in size, shape and fine structure. It is supposed that polymorphism could be partially explained by a different plasticity and premeability of cytoplasmic membrane in different types of cells of the same L-colony. The three-layer structure of the membrane does not always display the same distinctness in various L-colony cells and also in different areas of the cell surface. Structureless material of low electron density, possibly a defective murein or its precursor, was revealed on the membrane surface. Electrondense inclusion bodies, mesosomes of ring-shaped or more complicated structure and two-contour vesicles were found in the cytoplasm. The cells multiplied by budding, by binary and anomalies division participation of mesosomes in this process was not proved by the L-forms.