abnormal lung bud morphology absent lung buds 2011-03-04T02:59:58Z MP:0010907 MPheno.ontology absence of the blunt end of the respiratory diverticulum which normally grows ventrally out of the proximal end of the foregut, then extends caudally and divides into two, forming the origins of the bronchial tree absent primary lung buds absent tracheal buds csmith lung bud agenesis