Assertion: mediastinum's part | /r/CapableOf | leave primordium
Facets:
Source sentences:
text: During the embryonic developmental period of thyroid gland, part or all of the thyroid blastoma leaves primordium and is pulled into the thoracic cavity by the descendent heart and great vessels, then continues to develop in the thoracic cavity, forming the final primary intrathoracic goiter.