(...) at some stage of its development, every chordate exhibits five uniquely derived characters or synapomorphies of the group: (...) (4) a single, tubular nerve cord that is located dorsal to the notochord (...).[well established][VHOG]

An anatomical space that surrounded_by a neural tube.

UBERON:0005713

cavity of neural tube

neural tube neural lumen

lumen of neural tube

prosencoel

uberon

neurocoel

central lumen

neural lumen

UBERON:0003842