Parietal peritoneum is lined by

SIMPLE SQUAMOUS EPITHELIUM - The cells of this epithelium are flattened. In sections they appear so thin that bulgings are produced on the surface by nuclei. In surface view the cells have polygonal outlines that interlock with those of adjoining cells. A simple squamous epithelium lines the alveoli of the lungs, the free surfaces of peritoneum, pleura and pericardium. Here it is given the name mesothelium. It also lines the inside of blood vessels,where it is called endothelium, and Of the hea where it is called endocardium. REF : Inderbir Singh's Textbook of Human Histology, seventh edition, pg.no., 2.