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;
Ammonia can be converted to nitrite (NO 2) and nitrate (NO 3) by bacteria, and then used by plants. Nitrate and ammonia are the most common forms of nitrogen in aquatic systems. Nitrate predominates in unpolluted waters.