tissue homovanillic acid amount midbrain/pons homovanillic acid amount The proportion, quantity or volume in the midbrain (the middle of the three cerebral vesicles of the embryo or the corresponding part of the adult brain) and neighboring pons (between the medulla oblongata and the midbrain) of HVA, a catecholamine metabolite. VT:0010847 Trait.ontology midbrain/pons HVA amount 2019-10-30T13:12:57Z CMO:0003113 caripark brain homovanillic acid amount