• Applied Microscopy
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• v.37 no.4
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• pp.219-230
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• 2007

The morphological effects of intranasal zinc sulfate(5% solution) irrigation on the mouse olfactory epithelium and the regeneration process of olfactory receptor cells following nasal irrigation were studied with scanning and transmission electron microscope. The results were as follows: 1. The septal epithelium except some basal cells was wholly detached from the basement membrane, during the first 6 to 24 hours after 5% zinc sulfate irrigation. 2. 3 days after $ZnSO_4$ treatment, two layered septal epithelium was formed from basal cells. And microvilli were observed in the apical epithelium of newly formed olfactory epithelial cells. 3. 5 days after treatment, a lot of centrosomes and basal bodies were observed in the olfactory receptor cells, and cilia were lined up between microvilli on the apical membrane of olfactory receptor cells. And immature olfactory knob was first observed in the newly formed olfactory receptor cells. Mature olfactory knob was observed 1 week after treatment. 4. There are very many mature olfactory knobs in the olfactory receptor cells 2 weeks after intranasal zinc sulfate irrigation. These results support that treatment with 5% zinc sulfate is a good experimental model for the regeneration of mammalian nervous tissues because this method could thoroughly detach the septal epithelium. During the regeneration of olfactory receptor cells, the surface membrane of the olfactory receptor cells widen the surface with the microvilli. Then cilia, which arranged in a line, substituted for the microvilli. The part of the surface membrane with cilia protruded and finally formed the olfactory vesicle.

• The Korean Journal of Zoology
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• v.39 no.1
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• pp.54-64
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• 1996

Normal development of the olfactory placode was studied to describe the sequence of events involved in the development of the olfactory placode. It has been primarily concerned with the morphological differentiation of the sensory neurons, their initial growth, maturation patterns and the contacts of their axons with the primitive prosencephalic vesicle. The olfactory organ first appears at stage 23 as a paired thickening of the two ectodermal layers: the superficial non-nervous layer (NNL) and the inner nervous layer (NL). Receptor cells differentiate from the NL and the supporting cells develop from the NNL. After stage 26 the placodal cells begin to migrate toward the epithelial surface between the NNL cells and their apical processes reach the surface at stage 28. As the apical process reaches the epithelial surface, basal processes (presumptive axons) sprout from the base of the NL cells at stage 29/30. They penetrate the underlying telencephalon by stage 32. Sensory synaptic contacts first appear at stage 37/38. Some placodal cells remain at the olfactory epithelium as basal cells while other placodal cells differentiate into olfactory neurons. The results confirmed that neurons originate exclusively from the nervous layer of the ectoderm while supporting cells originate from the NNL layer. The results also indicate that the development of olfactory neuron is independent of information from the target ftssue.