mesopulmonum

mes·o·pul·mon·um

(mez'ō-pŭl'mon-ŭm),
The mesentery of the embryonic lung.
[meso- + L. pulmo, lung]

mesopulmonum

(mĕs″ō-pŭl-mō′nŭm)
The embryonic mesentery of the lung.