Three-Dimensional Structure and Disposition of the Air Conducting and Gas Exchange Conduits of the Avian Lung: The Domestic Duck (Cairina moschata)
Figure 5
Scanning electron micrographs showing the three dimensional architecture of the smaller air conduits and gas exchanging units. (a) and (b):The parabronchi (PB) have the typical honeycomb arrangement. Inerparabronchial vessels are visible between adjacent parabronchi (arrows in (a)). The large bronchial vein (V1) receives interparabronchial veins (V2) that run in the interparabronchial space (see (b)). (c) and (d):A close-up of the internal aspect of the parabronchi shows that the atria (ellipse in (c)) are extremely shallow and have 2-6 infundibulae (IF). The atria are surrounded by a ridge of epithelial tissue (white arrows in (d)), which is reinforced by smooth muscle characteristic of interatrial septa (see Figure 7). Some air capillaries emerge directly from the floor of the atrium (white arrowheads in (d)) while others are extensions from infundibulae.
