Scanning electron microscopic observation on olfactory epithelium of the mouse embryos *
To clarify development of the olfactory epithelium, ICR mouse nasal mucosa was examined from 12 days of gestation to 2 days after birth chiefly by scanning electron microscopy. On the basis of the appearance of olfactory vesicles and cilia. the development was divided into five stages. During stage Ⅰ. no olfactory vesicles could be found on the mucosa. During stage Ⅱ. a few solitary olfactory vesicles of various sizes appeared on the olfactory mucosa, then during stage Ⅲ, there was an increase in the number of vesicles. and they were gathered in small clusters. Durning stage Ⅳ. a decrease in the number of olfactory vesicles was noted. and short olfactory cilia were recognized on solitary vesicles. Durning stage Ⅴ. numerous long cilia were noted on the vesicles. The olfactory epithelium of mouse embryos was of three areas; lateral. nasoseptal and roof epithelium. At 12 days of gestation. the lateral olfactory epithelium was at stage Ⅰ. while the nasoseptal epithelium was at stage Ⅱ. The number of olfactory vesicles per unit area in the lateral area was significantly greater than that in the nasoseptal area(p＜0.01). At 16 days of gestation, the lateral epithelium was at stage Ⅳ. and nasoseptal was at stage Ⅴ. The nasoseptal epithelium seemed to develop approximately one day earlier than the lateral olfactory epithelium. The roof epithelium developed earlier to from an olfactory cilial mat at 16 days of gestation (Accepted on October 3, 2000) Kawasaki Igakkaishi 26(4) 211- 221, 2000
