What is "pleomorphism"

Pleomorphism \Ple`o*mor"phism\, n. [Gr. ? more + morfh` form.]

1. (Crystallog.) The property of crystallizing under two or more distinct fundamental forms, including dimorphism and trimorphism.

2. (Biol.) The theory that the various genera of bacteria are phases or variations of growth of a number of Protean species, each of which may exhibit, according to undetermined conditions, all or some of the forms characteristic of the different genera and species.

n. 1 (context biology English) the occurrence of multiple structural forms during the life cycle of an organism 2 (context chemistry English) polymorphism

1. n. (chemistry) the existence of different kinds of crystal of the same chemical compound [syn: polymorphism]

2. (biology) the appearance of two or more distinctly different forms in the life cycle of some organisms

In microbiology, Pleomorphism (from greek πλέω- more, and -μορφή form) is the ability of some bacteria to alter their shape or size in response to environmental conditions. Pleomorphism has been observed in some members of the Deinococcaceae family. The modern definition of pleomorphism in the context of bacteriology is based on variation of size or shape of the cell, rather than a change of shape as previously believed.

Pleomorphism may refer to:

• Pleomorphism (cytology): variability in the size and shape of cells and/or their nuclei
• Pleomorphism (microbiology): the ability of some bacteria to alter their shape or size in response to environmental conditions
• A life cycle of certain fungi where different stages have different morphology; see Teleomorph, anamorph and holomorph

Pleomorphism is a term used in histology and cytopathology to describe variability in the size, shape and staining of cells and/or their nuclei.

It is a feature characteristic of malignant neoplasms, and dysplasia. Certain benign cell types may have pleomorphism, e.g. neuroendocrine cells, Arias-Stella reaction.