Fig. 1.

Histological and SEM images illustrating the lobar organization of the embryonic lung. (A) A transverse section of the lung stained with H/E at day 34 pf. Two bronchi (arrows) on both sides of the esophagus (e) are seen. Note that the esophagus and the main bronchi are entirely surrounded by splanchnopleuric mesenchyme (m). Abundant blood cells are seen in the auricle (a). Pleural cavity (pc). Magnification, 20×. (B,C) SEM images of the lung at day 50 pf. Three pulmonary lobes can be seen in the right lung (B), and only two (numbered) in the left lung (C).