The epibranchial placodes in embryonic vertebrates are known to give rise to the sensory ganglionic cells of the facial, glossopharyngeal and vagal nerves that innervate taste buds, but the embryonic origins of taste buds, as well as the tissues that induce epibranchial placodes, remain unknown. Using new data on the development of the octavolateralis system, a new model of the development of the gustatory system is proposed. According to this model, epibranchial placodes are induced by chordamesoderm and/or paraxial mesoderm, and these placodes give rise to the progenitors of both taste buds adn sensory ganglionic cells. In order to test this model, extirpation and homotopic explanation of intracellularly labeled tissues involving chordamesoderm, epibranchial placodes, neural crest and neural plate are proposed. The experiments will be performed on embryonic axolotls, as the necessarily large number of embryos can be easily obtained, and these embryos are sufficiently robust to tolerate the experimental manipulations. Additional experimental neuroanatomical studies on the organization of the gustatory system of juvenile and adult axolotls will also be conducted in order to provide a more complete picture of this system.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC001081-03
Application #
3217797
Study Section
Sensory Disorders and Language Study Section (CMS)
Project Start
1991-04-01
Project End
1995-03-31
Budget Start
1993-04-01
Budget End
1994-03-31
Support Year
3
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Northcutt, R Glenn (2005) Taste bud development in the channel catfish. J Comp Neurol 482:1-16
Northcutt, R G; Barlow, L A; Braun, C B et al. (2000) Distribution and innervation of taste buds in the axolotl. Brain Behav Evol 56:123-45
Barlow, L A; Northcutt, R G (1998) The role of innervation in the development of taste buds: insights from studies of amphibian embryos. Ann N Y Acad Sci 855:58-69
Wicht, H; Northcutt, R G (1998) Telencephalic connections in the Pacific hagfish (Eptatretus stouti), with special reference to the thalamopallial system. J Comp Neurol 395:245-60
Rupp, B; Northcutt, R G (1998) The diencephalon and pretectum of the white sturgeon (Acipenser transmontanus): a cytoarchitectonic study. Brain Behav Evol 51:239-62
Barlow, L A; Northcutt, R G (1997) Taste buds develop autonomously from endoderm without induction by cephalic neural crest or paraxial mesoderm. Development 124:949-57
Barlow, L A; Chien, C B; Northcutt, R G (1996) Embryonic taste buds develop in the absence of innervation. Development 122:1103-11
Wicht, H; Northcutt, R G (1995) Ontogeny of the head of the Pacific hagfish (Eptatretus stouti, Myxinoidea): development of the lateral line system. Philos Trans R Soc Lond B Biol Sci 349:119-34
Northcutt, R G; Brandle, K (1995) Development of branchiomeric and lateral line nerves in the axolotl. J Comp Neurol 355:427-54
Barlow, L A; Northcutt, R G (1995) Embryonic origin of amphibian taste buds. Dev Biol 169:273-85

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