Photomicrographs from Zebra Finch and Herring Gull thyroid glands

(A) Photomicrograph from a Herring Gull (Larus argentatus) from Wisconsin shows a normal thyroid gland for comparison.  Within the thyroid gland there are variably-sized follicles filled lined by cuboidal epithelium (arrowhead) and filled with colloid (*). H&E stain. (B) Photomicrograph from a Zebra Finch (Taeniopygia guttata) from a California aviary that was found dead.  Follicular epithelium (arrowhead) is hyperplastic with abundant eosinophilic cytoplasm. Follicular lumina are small or indistinct and contain little or no colloid. H&E stain.