3 weeks: Brain interneurons send axons down brainstem to spinal cord and up to forebrain {interneuron development}. Axons transmit messenger chemicals to other neurons to integrate central nervous system. Medulla oblongata appears at neural-tube first flexure. Soon after, diencephalon appears at second flexure. Last neuroblast cells, having left-right asymmetry, migrate.
4-Zoology-Development-Stages-Gestation
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Date Modified: 2022.0225