“…During neuronal maturation, the nuclear morphology of the neuron changes from a small, heterochromatic nucleus with many randomly-located chromocenters and nucleoli, to a large, mostly euchromatic nucleus with fewer, larger chromocenters associated with a large, centrally located nucleolus [ 8 – 12 ]. This non-random reorganization suggests that these changes occur via clustering and relocation of these structures during terminal differentiation and these global chromatin changes have been observed in terminally differentiating neurons in a variety of species, strongly indicating functional significance [ 9 , 13 ]. Association of the human artificial chromosomes (HACs) with chromocenters is crucial for their stability in mouse cells, i.e.…”