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. in Some Species or in Specialized Cell Types RNA Metabolism or DNA Replication May Be Absent.
A Phospholipid Microvesicle That Is Derived From Any of Several Cell Types Such As Platelets Blood Cells Endothelial Cells or Others and Contains Membrane Receptors As Well As Other Proteins Characteristic of the Parental Cell. Microparticles Are Heterogeneous in Size and Are Characterized As Microvesicles Free of Nucleic Acids.