Fig. 3

Histological characteristics of the nasomaxillary aperture mucosa. a Overview illustrating the nasomaxillary aperture mucosa (A) with large veins (1) and artery (2), adjacent bone (B) and paranasal sinus mucosa (C); b Overview of lamina propria (A–C) arranged in three zones. A, subepithelial top area, and C, bottom area, contain many serous glands, while B, middle area, contains large veins (1) and an artery (2); c The mucosa shows pronounced folding (arrowheads). A: epithelium, B: lamina propria; d Detail of high, ciliated pseudostratified columnar epithelium (A) with multiple rows of nuclei. B: Lamina propria; Magnification see bars; Masson trichrome stain