Final answer:
During the embryonic period from weeks 4 to 16, the major lung structures have formed, including the branching of the bronchial buds which will later become bronchopulmonary segments within each lobe of the lungs.
Step-by-step explanation:
During the embryonic period, specifically from weeks 4 to 16, respiratory development undergoes significant changes. The lung bud appears very early in this phase, from which the bronchial buds form, eventually developing into the trachea and bronchi. As development progresses by around week 16, all of the major lung structures involved in the airway, including the respiratory bronchioles, have been formed.
Though the question does not specify the exact number, it's important to understand that these bronchial buds branch out considerably during the embryonic period. Thus, by the end of this period, each lung holds multiple branches which will later become segmented into bronchopulmonary segments, with each lobe housing several segments.