intravascular herein means within an internal tubular structure called a vessel that is connected to a tissue or organ within the body of an animal including mammals within the cavity of the tubular structure a bodily fluid flows to or from the body part examples of bodily fluid include blood lymphatic fluid or bile examples of vessels include arteries arterioles capillaries venules sinusoids veins lymphatics and bile ducts the intravascular route includes delivery through the blood vessels such as an artery or a vein afferent blood vessels of organs are defined as vessels in which blood flows toward the organ or tissue under normal physiologic conditions efferent blood vessels are defined as vessels in which blood flows away from the organ or tissue under normal physiologic conditions in the heart afferent vessels are known as coronary arteries while efferent vessels are referred to as coronary veins the term naked nucleic acids indicates that the nucleic acids are not associated with a transfection reagent or other delivery vehicle that is required for the nucleic acid to be delivered to a target cell a transfection reagent is a compound or compounds used in the prior art that mediates nucleic acids entry into cells parenchymal cells are the distinguishing cells of a gland or organ contained in and supported by the connective tissue framework the parenchymal cells typically perform a function that is unique to the particular organ the term u201c parenchymal u201d often excludes cells.