Fig. 4
From: A sodium binding system alleviates acute salt stress during seawater acclimation in eels
Periodic acid–Schiff (PAS), Alcian blue stainings of esophagus (Eso), skin, gill, and middle intestine (MI) of eels acclimated to FW (a, g, i, k, m, o) or SW after 3 h (b, h, j, l, n, p), 12 h (c), 1 d (d), 3 d (e) 7 d (f). PAS- and Alcian blue (pH 2.5)-positive mucus cell (MC) density increased rapidly 3 h after SW transfer in Eso. Alcian blue (pH 1.0) staining was negative in the esophageal epithelia. Mucus mass (MM) with desquamated cells are prominent in the lumen (Lu) during early transfer (from SW 3 h – SW 1 d) in Eso. Absorptive columnar cells (CC) are present on the esophageal villi after 7 d in SW. Arrow heads indicate the mucus layer thickening after SW transfer. Sc = scale; Fi = filament; Lm = lamellae. Scale bar = 200 μm