Motor neurons in the tunicate caudal central nervous system reveal homology to the vertebrate spinal cord

Kourakis, Matthew J.; Ryan, Kerrianne; Newman-Smith, Erin D.; Meinertzhagen, Ian A.; Smith, William C.

doi:10.1242/dev.204525

Motor neurons in the tunicate caudal central nervous system reveal homology to the vertebrate spinal cord

Journal Article · Thu Mar 13 00:00:00 EDT 2025 · Development (Cambridge)

DOI:https://doi.org/10.1242/dev.204525· OSTI ID:2530779

Kourakis, Matthew J.; Ryan, Kerrianne; Newman-Smith, Erin D.; Meinertzhagen, Ian A.;

ABSTRACT

Invertebrate chordates, such as the tunicate Ciona, can offer insight into the evolution of the chordate phylum. Anatomical features shared between invertebrate chordates and vertebrates may be taken as evidence of their presence in a common chordate ancestor. The central nervous systems (CNSs) of Ciona larvae and vertebrates share a similar anatomy despite the Ciona CNS having only ∼180 neurons. However, the depth of conservation between the Ciona CNS and those of vertebrates is not resolved. The Ciona caudal CNS, while appearing spinal cord-like, has hitherto been thought to lack motor neurons, bringing into question its homology with the vertebrate spinal cord. We show here that the Ciona larval caudal CNS does, in fact, have functional motor neurons along its length, pointing to the presence of a functional spinal cord-like structure at the base of the chordates.

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Sponsoring Organization:: USDOE

Grant/Contract Number:: SC0021978

OSTI ID:: 2530779

Journal Information:: Development (Cambridge), Journal Name: Development (Cambridge) Journal Issue: 5 Vol. 152; ISSN 0950-1991

Publisher:: The Company of BiologistsCopyright Statement

Country of Publication:: United Kingdom

Language:: English

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