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Nervous system of ascidian larvae: Caudal primary sensory neurons

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Summary

In larvae of Diplosoma macdonaldi one sensory nerve extends along the dorsal midline of the tail and another extends along the ventral midline. Each nerve is composed of 50–70 naked axons lying in a groove in the base of the epidermis, and each projects to the visceral ganglion. The cell bodies of the caudal sensory neurons occur in pairs within the epidermis, and are situated along the courses of the nerves. A single cilium arises from an invagination in the soma of each neuron, passes through the inner cuticular layer of the tunic and enters a tail fin formed by the outer cuticular layer. We propose that these cells are mechanoreceptors. The caudal sensory system is similar in representative species of ten families of ascidians.

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Abbreviations

a :

axial complex of the tail

ac :

accessory centriole

ax :

axon

bb :

basal body

bl :

basal lamina

c :

cilium

cep :

common epidermal cells

cs :

ciliary sheath

dcv :

dense-cored vesicles

dsn :

dorsal sensory nerve

ec :

ependymal cells

ep :

epidermis

gj :

gap junction

h :

hemocoel

hc :

hemocoelic chamber

icl :

inner cuticular layer of the tunic

m :

caudal muscle

nc :

dorsal nerve cord

ncl :

neurocoel

no :

notochord

ocl :

outer cuticular layer of the tunic

sc :

sensory cell

sn :

sensory nerve

sv :

sensory vesicle

vg :

visceral ganglion

vsn :

ventral sensory nerve

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Authors and Affiliations

  1. Department of Zoology, University of Washington, 98195, Seattle, Washington, USA

    Steven A. Torrence & Richard A. Cloney

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  1. Steven A. Torrence
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  2. Richard A. Cloney
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Torrence, S.A., Cloney, R.A. Nervous system of ascidian larvae: Caudal primary sensory neurons. Zoomorphology 99, 103–115 (1982). https://doi.org/10.1007/BF00310303

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  • DOI: https://doi.org/10.1007/BF00310303

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