The early development of sino-nasal mucosa.

The development of human nasal mucosa was studied in 20 fetal heads between 8 and 24 weeks of gestation. Initially the nasal cavity is lined by a single layer of flattened cells, which produces two to three layers of undifferentiated spherical cells. Olfactory epithelium lines the cranial portion of the human fetal nasal cavity at 8 weeks of gestation. Pseudostratified ciliated cuboidal or columnar epithelium appears at 9 weeks of gestation in the nasal cavity and between 14 and 16 weeks of gestation in the primitive ethmoid sinuses and maxillary sinus infundibulum. Goblet cells and glandular acini appear between 12 and 14 weeks of gestation. Initially these goblet cells/glands are found predominantly in the anterior nasal cavity but are more evenly distributed at 24 weeks of gestation. The epithelial development of the nasal septum generally precedes that of the lateral nasal wall. This study documents nasal mucosal maturation and associated anatomic development in the human fetus.