chapter  2
56 Pages

II. THE FIRST TRIMESTER ------------------------------------------------------------

Areas (mm2) Spinal canal .0046 Neuroepithelium .0459 Roof plate .0021 Floor plate .0023 Primordial white matter

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Roof plate

Floor plate

Dorsal neuroepithelium (alar plate)

Intermediate neuroepithelium

Ventral neuroepithelium (basal plate)

Slit-shaped spinal canal

Mitotic figures in neuroepithelium

Earliest differentiating motoneurons?