Remodeling of the olfactory mucosa: maturation of glia, fibroblasts and vascular compartments after birth

Despite extensive research on the olfactory epithelium during embryonic and postnatal stages, little is known about peripartum adaptations. Here we describe the profound changes that occur between E18 and P8 - shortly after birth and exposure to air. In the lamina propria, we observed a significant expansion of extracellular space and axon bundles. Olfactory ensheathing cells, the glia cells of the lamina propria, stopped proliferating and upregulate SOX10 after birth. In addition, only after birth did olfactory ensheathing cells express CLDN5 and PECAM1, both of which tighten blood vessels, as well as gap junction communication and potassium transport proteins. Functional Bowman glands emerged only after birth, similar as the layer of horizontal basal cells. Since horizontal basal cells produce extracellular matrix proteins, laminin localization changed after these cells populated the basal epithelium. Interestingly, embryonic mice showed multiple invaginations of blood vessels throughout the olfactory epithelium, which disappear immediately after birth. Our findings reveal that the lamina propria of the olfactory mucosa undergoes profound postnatal maturation, leading to the establishment of a specialized adult tissue architecture.