Fig. 5.

Schematic representation of the present results. At 7 weeks, except for B7, the bronchial tree in the right lower lobe has already developed at the subsegmental level: B6a, B6b, B6c, B8a, B8b, B9a, B9b, B10a, B10b, B10c. However, the inferior pulmonary vein (IPV) is thin and difficult to identify in the segmental level. At 8 weeks, the vein reaches each of the segments. At 15 weeks, in some specimens, B7 is seen crossing the anterior side of the vein.