ANALYSIS OF NEUROGENESIS AND AGING IN OLFACTORY EPITHELIUM IN RAT

• Published in: JIBI INKOKA TEMBO Vol. 37; no. 1; pp. 22 - 40
• Main Author: Kitagawa, Kazuhisa
• Format: Journal Article
• Language: Japanese
• Published: Society of Oto-rhino-laryngology Tokyo 1994; 耳鼻咽喉科展望会
• Subjects: aging; immunohistochemistry; N-CAM MAP; neurogenesis
• ISSN: 0386-9687; 1883-6429
• DOI: 10.11453/orltokyo1958.37.22

The neurogenesis and aging of the olfactory epithelium in rat were investigated with immunohistochemical and electron microscopic methods. The rats used in this study were embryonic day 19, postnatal day 3, adult, and aged rats. Anti-N-CAM (neural cell adhesion molecule), anti-MAP 5 (microtubule associated protein 5) and anti-MAP 2 antibodies were used for immunohistochemical method. In the adult rats, N-CAM and MAP 5 immuno-positive stainings were exclusively found in the basal and middle layer of the epithelium and the axons in the lamina propria. Immunoreactivity to anti-MAP 2 was found throughout the olfactory cell layer of the epithelium. In the embryonic and neonatal rat, the positive stainings of anti-MAP 5 were located in the olfactory cell layer of the epithelium, occupying a position closer to the epithelial surface. In the neonatal rats, the cells which differentiated in the embryonic period immigrate towards the free surface. The grade of the maturation of MAP 5-positive cells is thought to be not high. I consider that the cells in the basal and middle layers were less developed than the MAP 5-positive cells, although the morphological structure appeared almost fully developed. MAP 2 was only detectable near the free surface of the epithelium. From their flask-like shape, these cells might be the so-called “microvillar cell”. In the aged rats, the immunoreactivity to anti-MAP 2 was similar to the adult rats. Thus, I speculate that aged rats may have maintained their olfactory acuities. However, on the electron microscopic observation, the thickening of the basement membrane and the decrease in the number of olfactory cells were observed, indicating an age-related change. Furthermore, in the epithelium, the immunoreactivity to anti-NCAM was weak. Therefore, it is thought that the supply of new neurons is not as plentiful as in the younger rats.