TODO - add grouping class for the anterior end of the neural tube at all stages

uberon

(...) 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]

UBERON:0003080

• presumptive midbrain
• forebrain

• forebrain midbrain boundary neural tube
• forebrain neural tube
• midbrain neural tube