substantia nigra morphology trait substantia nigra molecular composition trait 2025-10-14T18:10:11Z Any measurable or observable characteristic related to the proportions of proteins, minerals, nutrients, gases, or other substances in the substantia nigra of the brain, the layer of grey substance that separates the posterior parts of the cerebral peduncles (tegmentum mesencephali) from the anterior parts; it normally includes a posterior compact part with many pigmented cells (pars compacta) and an anterior reticular part whose cells contain little pigment (pars reticularis). Trait.ontology VT:0011229 midbrain molecular composition trait