teratoma. [terâ²ÉtÅâ²mÉ] pl. teratomas, teratomata. a tumor composed of different kinds of tissue, none of which normally occurs together or at the site of the tumor. Teratomas are most common in the ovaries or testes.
The pink-colored film or ring frequently seen on showers, tubs, toilets and pet water bowls is typically caused by growth of the airborne bacteria Serratia marcesens. This harmless nuisance organism reacts with standing water and frequently forms during spring and summer months.
Gram negative bacteria (stain pink!) have a lipopolysaccharide layer above the peotidoglycan layer which do stain violet with crystal violet, but are washed off by the ethanol treatment. The peptidoglycan layer beneath remains untouched by the crystal violet stain and is now free to take up the pink color of safranin.