Photograph and photomicrographs from a Pacific loon (Gavia pacifica) found dead in Alaska

Photograph and photomicrographs from a Pacific loon (Gavia pacifica) found dead in Alaska, USA (A) The proventriculus (arrows) is enlarged and the serosal aspect contains many raised serpentine tracts. An asterisk (*) indicates the ventriculus. (B) The outer tunica muscularis of the proventriculus is expanded by several nematodes within cavities lined by epithelioid macrophages and eosinophilic material (granulomas). Nematodes have a smooth cuticle (arrow), coelomyarian-polymyarian musculature (*), a pseudocoelom, and a pseudomembrane (arrowheads). H&E stain. (C)  Detail of (B). Note the coelomyarian-polymyarian musculature (*) and prominent ventral nerve chord (arrow). The nematode is surrounded by hemorrhage and bacteria (arrowhead). H&E stain.  (D) Eggs are oval, thick-shelled, mamillated, and operculated (arrowhead). H&E stain.