Degeneration Process of Fungiform Taste Buds After Severing the Human Chorda Tympani Nerve—Observation by Confocal Laser Scanning Microscopy

Abstract

Confocal laser scanning microscopy was useful for clarifying the degeneration process of fungiform taste buds.

Relationship between gustatory function and average number of taste buds per fungiform papilla measured by confocal laser scanning microscopy in humans

“…In the PS group, many subjects with a severed CTN were included. After the CTN was severed, all taste buds had degenerated and disappeared 50 days after surgery (21). In the present study, regenerated taste buds were detected using confocal laser scanning microscopy in 40% of the patients with a severed nerve.…”

Long-term Follow-up Results of Regeneration Process of Fungiform Taste Buds After Severing the Chorda Tympani Nerve During Middle Ear Surgery

“…13 Recently, the degeneration process of fungiform taste buds after severing the human CTN has been reported using confocal laser microscopy. 6 In 7 patients with a severed CTN, taste buds had completely disappeared at around 50 days on average after surgery. Further observation of the postoperative course of these patients will make it possible to elucidate when the taste buds regenerate and whether the number of regenerated taste buds continuously increases for 1 to 2 years after surgery.…”

“…These 7 patients were the same as in our previous report in whom the degeneration process of fungiform taste buds was clarified after severing the CTN. 6 In this study, their FP were periodically observed by a confocal laser scanning microscope until 12 to 24 months after surgery. However, the 7 patients were not overlapped with those in other reports on the regeneration of fungiform taste buds.…”

“…The detailed method was described elsewhere. [4][5][6]10 EGM thresholds were -6 (4 μA) to 34 dB (400 μA) in 2-dB increments. "No response" signified that the threshold was beyond the measurable range and was statistically considered as 36 dB.…”

“…Since taste buds of the fungiform papillae (FP) on the dorsal surface of the anterior two-thirds of the tongue are innervated by the chorda tympani nerve (CTN), 1 the number of FP decreases 2,3 and the taste buds disappear after severing the nerve in the middle ear. [4][5][6] For a long period, it has been believed that no spontaneous regeneration of the CTN and taste buds occurred after transection of the CTN in the middle ear. 7 Since the 2000s, however, it has been reported that both the CTN and taste buds could regenerate following nerve reconstruction during middle ear surgery.…”