[A study of Proteus L forms during reversion by means of electron microscopy and ultrathin sections]

The method of scanning electron microscopy was applied to the study of the Proteus L-forms which reversed directly on the millipore filters. It appeared that reversion was accompanied by elongation of the cell, piriform cells forming as the result. Filamentous cells segmented into short fragments and large bodies with a spongy surface structure with numerous ruptures were also revealed in the reversing culture. The method of ultrathin sections showed the other membrane in many cells to be fragile and readily twisting forming vesicles collecting into chains. As supposed, this is connected with degenerative changes involving the outer membrane of the paternal L-forms at the early reversion periods. An interrupted structure of the outer membrane was also demonstrated in many cells. It is supposed that in this case a synthesis of the outer membrane de novo at the later stages of reversion is dealt with. Phenomenon of "extrusion" of the multilayer structures into the periplasmic space, characteristic of spheroplasts, is described. A marked similarity of the morphological picture of reversion and at the initial stages of L-transformation, i.e. of the processes representing a looking glass reflection of one another, is described.