Late Neurula Stage
General shape of the embryo:
- -Trunk/tail constriction visible
Size:
- ~ 200 µm
Neural Tube:
- Complete neurulation of neural plate A-line cells.
- Dorsal and ventral cells intercalate leading to a caudal neural tube formed by four cells (see scheme of a transverse section, arrows indicate dorsal and ventral cell intercalation in the caudal neurectoderm)
Notochord:
- Notochord is formed by a sheath of square-shaped cells in the periphery and a mass of round internal cells. Approximately three cells occupy the width of the notochord
Ectoderm:
- In the presumptive caudal region, cells join to the dorsal midline and do not intercalate