part of part of has part has part in_lateral_side_of pleura respiratory system lower respiratory tract pleural cavity endoderm-derived structure serous sac pleural sac A serous sac that has the pleura and the pleural cavity as parts. EHDAA2:0004737 FMA:9690 UBERON:0009778 despite its name the class EHDAA2:0004737 is not a true cavity, it corresponds to what we call the sac uberon lateral structure