what epithelial tissue lines the serous membranes
/mesoÂ·theÂ·liÂ·um/ (-theÂ´le-um) the layer of cells, derived from mesoderm, lining the body cavity of the embryo; in the adult, it forms the simple squamous epithelium that covers all true serous membranes (peritoneum, pericardium, pleura).mesotheÂ´lial.