has part has part characteristic of has modifier Abnormal putamen morphology Agenesis of putamen The basal ganglia are symmetrical subcortical gray nuclei at the core of the extrapyramidal system, composed by the striatum (which comprises the putamen, caudate nucleus, olfactory tubercle, and nucleus accumbens), the pallidum, the substantia nigra, and the subthalamic nucleus. Congenital malformations of the basal ganglia deriving from defects of embryogenesis are very rare. The basal ganglia embryologically derive from the prosencephalon (or forebrain), the most rostral of the three vesicles originating from early patterning of the neural tube along the anterior-posterior axis. abnormal agenesis putamen