abnormal cell morphology abnormal cell nucleus morphology any structural anomaly of a membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated; in most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing, but in some species, or in specialized cell types, RNA metabolism or DNA replication may be absent MP:0003111 MPheno.ontology abnormal nucleus morphology abnormal nuclear compartment morphology