sub·stan·tia ni·gra səb-.stan-chē-ə-'nī-grə, -'nig-rə n, pl sub·stan·ti·ae ni·grae -chē-.ē-'nī-(.)grē, -'nig-(.)rē a layer of deeply pigmented gray matter situated in the midbrain and containing the cell bodies of a tract of dopamine-producing nerve cells whose secretion tends to be deficient in Parkinson's disease
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[TA] black substance: the layer of melanin-containing neurons that separates the tegmentum of the midbrain from the crus cerebri; it includes a posterior compact part with many pigmented dopaminergic cells (pars compacta) and an anterior reticular part whose cells contain little pigment (pars reticularis).
Substantia nigra in a section through the rostral midbrain.
Medical dictionary. 2011.