Fig. 6

Structural differences in the upper and lower eyelids across Strigiformes. (a) and (o) – Boreal Owl; (b) and (j) – Eurasian Eagle-Owl; (c) and (r) – Ural Owl; (d) and (k) – Little Owl; (g) and (l) – Tawny Owl; (h) and (m) – Philippine Scops-Owl; (g) and (p) – Northern Hawk Owl; (h) and (n) – Snowy Owl; (i) and (s) – Western Barn Owl. aps – anterior palpebral surface, e – epithelium, fs – folds of skin, lp – lamina propria.a – j, j, l – n = Mayer’s H&E stain; o – s = Movat pentachrome (modified Russell-Movat) stain; k = picro-Mallory trichrome stain. Scale bars: j, n, r = 200 μm; k – m, p, s = 100 μm; o = 50 μm; c, d, f, i = 20 μm; a, b, e, g, h = 10 μm