Fig. 2

Histological characteristics and differences of the paranasal sinus mucosa in representative sample sites. a Overview illustrating all tissue layers of the DCS; b Overview illustrating the mucosa layers of the RMS; c Detail of epithelium displaying cilia on the surface (arrowheads) and several rows of nuclei [FS]; d Detail showing a thin mucus layer on the luminal surface of the ciliated pseudostratified columnar epithelium (arrowheads) with goblet cells [VCS]; e, f Age-related and topographical differences of the paranasal sinus mucosa (see Table 2): e Sample of the CMS from a 2 years old horse; f Sample of the MCS from a 12 years old horse. f A lower mucosal height, lower epithelial height and higher number of goblet cells compared to (e). A: Paranasal sinus mucosa; B: bone plate; C: nasal mucosa, 1: ciliated pseudostratified columnar epithelium; 2: lamina propria; 3: periosteum; 4: adjacent bone; 5: goblet cells; 6: blood vessel; 7: serous glands. CMS caudal maxillary sinus, DCS dorsal conchal sinus, FS frontal sinus, MCS middle conchal sinus, RMS rostral maxillary sinus, VCS ventral conchal sinus. Magnification see bars; Masson trichrome stain