Douma, S. (Sytze) (2018) Cochlear anatomy in naked and Damaraland mole rats. thesis, Medicine.
Full text available on request.Abstract
Compared to many other rodent species, naked mole rats (Heterocephalus glaber) have elevated auditory thresholds, poor high frequency hearing, and limited ability to localize sound. Differences in the peripheral and central auditory structures that underly differences in their auditory function are poorly understood. Because the cochlea is responsible for encoding and relaying auditory signals to the brain, we used immunofluorescence and quantitative image analysis to examine cochlear anatomy and especially innervation in mature and developing naked mole rats compared to mice (Mus musculus), gerbils (Meriones unguiculatus), and Damaraland mole rats (Fukomys damarensis), another subterranean rodent. In comparison to mice and gerbils, we observed alterations in afferent and efferent innervation as well as their patterns of developmental refinement in naked and Damaraland mole rats; however, these alterations were not always shared similarly between naked and Damaraland mole rats. Most conspicuously, in both naked and Damaraland mole rats, inner hair cell afferent ribbon density was reduced, whereas outer hair cell afferent ribbon density was increased. Naked mole rats also showed reduced lateral and medial efferent terminal density. Developmentally, naked mole rats showed reduced and prolonged postnatal reorganization of afferent and efferent innervation. Damaraland mole rats showed no evidence of postnatal reorganization. Finally, BK channel expression in inner hair cells, an indicator of developmental maturation in other rodents, was reduced and, furthermore, showed no tonotopic variation in naked mole rats. These alterations in cochlear anatomy in naked and Damaraland mole rats may result from neotenous maintenance of immature cochlear anatomy that serves to adapt hearing to their unique subterranean environments. Importantly, these findings establish naked and Damaraland mole rats as comparative species worthy of future investigation to examine cochlear mechanisms that support high frequency hearing and sound localization.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Faculty supervisor: Sonja J. Pyott and Institution: University of Groningen, University Medical Cen and Department of Otorhinolaryngology and Head/Neck Surgery |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 11:07 |
| Last Modified: | 25 Jun 2020 11:07 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/2636 |
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