The central nervous system of ascidian larvae.
Level 5 - mechanism / opinion, no new human data
Narrative review of non-human developmental biology (level 5 by design analogy)
PubMed 27328318 · doi:10.1002/wdev.239
What was done
This narrative review summarizes research on the structure, cell lineage, and developmental genetics of the central nervous system (CNS) in ascidian (marine invertebrate chordate) tadpole larvae, detailing progress in understanding neural induction, neural plate patterning, neurulation morphogenesis, and cell fate specification.
What was found
The ascidian larval CNS develops via the rolling up of a neural plate into a dorsal tubular structure containing approximately 330 cells in total, of which around 100 are neurons. Along the anterior-posterior axis, it is organized into four regions: sensory vesicle, neck, trunk ganglion, and tail nerve cord. Due to invariant cell division patterns, complete lineages have been mapped for specific cell types. Molecular mechanisms specifying trunk ganglion cholinergic neurons and sensory pigment cells are elucidated. No other quantitative values were reported in the abstract.
Why it matters
Because ascidian larvae share chordate CNS organization but have a minimal, fixed number of cells, they provide a uniquely tractable model for dissecting nervous system development from induction to single-neuron specification.
Limits
This is a narrative review without systematic search criteria or formal risk-of-bias evaluation. It reports no new empirical data, and findings from invertebrate chordates may not directly generalize to vertebrate CNS complexity.
Cited by
- context A species of ocean animal (such as a sea squirt) absorbs or digests its own brain after permanently settling onto a rock.