Abstract: Katarina DITTRICH

Metamorphotic remodeling of the olfactory organ of the African clawed frog Xenopus laevis

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Katarina Dittrich (1), Thomas Hassenklöver (1 ,2), Alfredo Sansone (1), Ivan Manzini (1 ,2)

(1) Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
(2) Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany

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The fully aquatic larvae of Xenopus laevis have an anatomically segregated main and accessory olfactory system. The larval main olfactory epithelium is located in the so-called principal cavity (PC), the epithelium of the accessory system is situated in the vomeronasal organ (VNO). During metamorphosis, a second cavity, the middle cavity (MC), also lined with sensory epithelium develops and a drastic reorganization of the epithelium of the PC takes place. In larvae, sensory neurons of the PC are used to detect waterborne odorants, but after metamorphosis the PC is thought to act as an 'air nose'. The MC very likely serves as a ‘water nose’. The VNO, like in the larval stages, is filled with water also in the adult frog.

Combining nerve backfills, in vivo electroporation, functional calcium imaging, immunohistochemistry, and a bromo-2'-deoxyuridine incorporation assay, we monitored the metamorphotic changes of the olfactory organ of Xenopus laevis. We first undertook a thorough examination of the anatomical changes of the olfactory cavity. We then set out to answer the question whether sensory neurons of the PC and the VNO are retained and or replaced. We investigated if sensory neurons are respecified and to which extent the sensory neurons of the MC are newly formed during metamorphosis. Finally, we monitored the gradual relocation of the responses of a group of waterborne odorants (L-amino acids) from the larval PC to the adult MC. Together our findings illustrate the structural and functional changes of the olfactory organ during larval development.