_Endoderm of proximal/cranial end of LT tube and cartilage from neural crest origin
_Formation of proximal larynx – cranial tube
�Arytenoid
swellings grow towards tongue
�Airway
gets closed off, eventually recanalizes
_Laryngeal webs – Incomplete recanalization
_Laryngeal atresia – ascites, hydrops and lungs do not properly form.