Histologic Study on the Development of Olfactory Mucosa in Rats

ABSTRACT

BACKGROUND AND OBJECTIVES: There is evidence which suggests that mammals have functional olfactory systems at birth or shortly before birth. This study was performed to investigate perinatal development of the olfactory mucosa. MATERIALS AND METHODS: Sprague-Dawley rats at the 19th gestational day, and of the 1st, 3rd, 7th, 14th, 21st, and 28th postnatal day were sacrificed. The light microscopic investigation of the olfactory mucosa was conducted with hematoxylineosin stain, immunohistochemical stain for proliferating cell nuclear antigen (PCNA) and protein gene product (PGP) 9.5. RESULTS: Number of the cell layers, epithelial thickness, and density of the olfactory receptor cell peaked at the postnatal 14th day. The cells of the basal layer changed from globose cells to basal cell proper with age. The number of the basal cells to the receptor cells decreased with age. PCNA was positive both in the supporting and basal layers. PCNA positivity decreased with age in the supporting layer but stayed stationary in the basal layer. PGP 9.5 was strongly positive in the olfactory receptor cells, dendrites, and the nerve bundles but negative in the supporting and basal layers. CONCLUSION: The olfactory epithelium proliferated maximally at postnatal 14 day, and afterwards the olfactory mucosa tended to show their characteristic maturation with slowed neurogenesis.