BACTERIAL PERSISTENCE. “Essential to the thesis is that small, electron dense, non-vesiculated L-forms are the central (core) element in bacterial persistence. Depending on the stimulus received, these dense forms might be considered as undifferentiated cells, with the capacity to develop along several different routes.”
http://www.discoverymedicine.com/Gerald-J-Domingue/2010/09/23/demystifying-pleomorphic-forms-in-persistence-and-expression-of-disease-are-they-bacteria-and-is-peptidoglycan-the-solution/