Which epithelium forms the endothelium that lines the tunica intima?

1. The innermost tunic of a vessel is the tunica intima, and its lining cell layer is the endothelium. 2. That endothelium is a specialized simple squamous epithelium, one flat cell thick. 3. The same lining runs unbroken through the whole vascular system, including the chambers of the heart. 4. Columnar, cuboidal and pseudostratified linings sit in airways and glands, not on the luminal face of a vessel. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 20 "The Cardiovascular System: Blood Vessels and Circulation", section 20.1 Structure and Function of Blood Vessels_