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-positive bacteria have a thick mesh-like cell wall made of peptidoglycan (50â90% of cell envelope), and as a result are stained purple by crystal violet, whereas gram-negative bacteria have a thinner layer (10% of cell envelope), so do not retain the purple stain and are counter-stained pink by the Safranin.