Graduation Date

Spring 2023

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

John Reiss

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Sharyn Marks

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Karen Kiemnec-Tyburczy

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Allison Bronson

Fourth Committee Member Affiliation

HSU Faculty or Staff

Subject Categories



The olfactory system of living amphibians (Lissamphibia) undergoes major changes as it transitions from an aquatic to a terrestrial system during metamorphosis. Patterns of change in the cellular morphology of the nose have been examined for frogs (Anura) and salamanders (Caudata). However, it remains unknown if caecilians (Gymnophiona) have similar patterns of change in their nasal ultrastructure. In particular, no data on larval caecilian olfactory cell types are available. Here, using light microscopy and transmission electron microscopy, I examined the olfactory organ of larvae of the caecilian Ichthyophis kohtaoensis, to establish the ultrastructure of the epithelium and compare it to that of other amphibians. I found that there are microvillar receptor cells, ciliated receptor cells, and secretory supporting cells in the main olfactory epithelium (MOE) of I. kohtaoensis. However, in the posterior portion of the main olfactory cavity (MOC), the cells appear disorderly and “loose” with a haphazard orientation, in comparison to the anterior portion of the cavity where cells are neatly arranged and closely packed. There are only ciliated receptor cells and secretory supporting cells in the posterior MOC. The vomeronasal organ (VNO) of I. kohtaoensis has microvillar receptor cells, secretory supporting cells, ciliated supporting cells, and supporting cells with both cilia and microvilli. Interestingly, similar cell types and a disorderly appearance of the posterior main olfactory epithelium have also been described in adult Typhlonectes compressicauda, the only other caecilian for which ultrastructural data exist. Apart from I. kohtaoensis not having any ciliated supporting cells in the main olfactory cavity, the epithelium of both the MOC and the VNO resembles that of other amphibian larvae.

Citation Style

Journal of Morphology

Included in

Zoology Commons


Thesis/Project Location


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