Fig. 3

Third eyelid structural similarities in Strigiformes (a, d, g, j, m), Accipitriformes (b, e, h, k, n), and Falconiformes (c, f, i, l, o). (a) – Eurasian Eagle-Owl; (b) – White-tailed Eagle; (c), (i) and (o) – Peregrine Falcon; (d) – Snowy Owl; (e) – Eurasian Sparrowhawk; (f) and (l) – Eurasian Kestrel; (g) – Boreal Owl; (h) – Hen Harrier; (k) – Eurasian Goshawk; (j) and (m) – Northern Hawk Owl; (n) – Steppe Eagle. bfs – bulbar folds, bs – bulbar surface, bv + m – blood vessels and melanocytes, e – epithelium, dct – dense connective tissue, mp + le–marginal plate and leading edge, pfs – palpebral folds, ps – palpebral surface. a, c, f – i, k, l, n, o = Mayer’s H&E stain; b = Masson Goldner trichrome stain; d, j, m = Movat pentachrome (modified Russell-Movat) stain; e = picro-Mallory trichrome stain. Scale bars: m = 100 μm; j, k, n, o = 50 μm; b, c, g, l = 20 μm; a, d, e, f, h, i = 10 μm