Search
Presentation Details
| Poster #158 Degrading Synapses in the Taste Bud |
| Courtney E Wilson, Yannick Dzowo, Rob Lasher, Thomas E Finger University of Colorado School of Medicine Department of Cell and Developmental Biology, Aurora, CO, United States |
The epithelial-derived taste cells of taste buds are renewed continuously throughout life. New, post-mitotic cells enter at the base of the bud, while older cells eventually die. To accommodate this renewal, taste nerve fibers must continuously remodel, separating from dying taste cells and forming synapses with new taste receptor cells. Here, using a high resolution, volumetric dataset attained by serial blockface scanning electron microscopy (sbfSEM), we examine the ultrastructural aspects of presumed degrading synapses between dying taste cells and nerve fibers. Many dying taste cells, as identified by ultrastructural features consistent with apoptosis, maintain recognizable synaptic structures at points of contact with afferent nerve fibers. In dying Type II cells, the atypical mitochondria that mark synapses are present, but their cristae appear more irregular or “loose” compared to the tightly packed tubular cristae of healthy Type II cells. In dying Type III cells, points of contact with nerves feature clusters of irregular vesicles larger (30-300 nm in diameter) than typical 40-60 nm synaptic vesicles. Whether these degenerating synapses are capable of synaptic transmission is unknowable with our current methods. Interestingly, many of the afferent nerve fibers appear to be nerve fiber fragments that no longer connect to the main intragemmal nerve fiber network. Such fragments suggest that nerve fragmentation may be a part of the nerve remodeling process. |