Fig. 2.

Elastica van Gieson (EVG) and trichrome (TRI) stain. (A) Schematic of the syrinx frontal section. (B) Section of the pessulus, ML and MTM. The square indicates the location of the higher magnification images in D–G. (C) Control stains for EVG (upper square) and TRI (lower square). In D–G, the tracheal lumen is to the left and the air sac lumen is to the right. (D) EVG stain in three specimens of the WCS. Note that most of the elastic fibers in the WCS are concentrated near the air sac side of the labium. (E) Masson’s TRI stain in three specimens of the WCS. The arrows indicate a local concentration of blue-stained collagen fibers. (F) EVG stain in three specimens of the ZF. (G) Masson’s TRI stain in three specimens of the ZF. P, pessulus; SL, superficial layer; DL, deep layer. Bar: 100 μm.