A malignant fibrous histiocytoma with a predominance of myxoid areas that resemble primitive mesenchymal tissue. [myxo- + L. fibra, fiber, + G. sarx, flesh, + -Åma, tumor]. /myxoÂ·fiÂ·broÂ·sarÂ·coÂ·ma/ (-fiâ³bro-sahr-koÂ´mah) older term for the myxoid subtype of malignant fibrous histiocytoma.
1 Ammonium ion (NH4+), the most reduced natural specie of nitrogen, and the most biologically available in an oxygen-less environment;  Nitrate ion (NO3-), the most oxidized form of nitrogen and mostly usable in an aerobic environment;
One such form is ammonia (NH3). Ammonia may be taken up by plants or oxidized by bacteria into nitrate (NO3-) or nitrite (NO2). Ammonia (NH3+) is a colorless gas with a strong pungent odor. Ammonia will react with water to form a weak base. The term ammonia refers to two chemical species which are in equilibrium in water (NH3, un-ionized and NH4+, ionized). Tests for ammonia usually measure total ammonia (NH3 plus NH4+).