Microtubular structures in group D streptococcal L-forms

Summary Microtubular structures, apparently continuous with the plasmalemma, have been observed in thin sections of two strains of group D streptococcal L-forms. The tubules had an external diameter of about 250 Å and a hollow core 100–150 Å in diameter. The tubules were found protruding either into or out of the L-form cells and were only found in cultures growing in the presence of penicillin.