Eventually , the development of the notochord canal and the axial canal takes place between days 17 and 19 when the first three somites are formed .
The notochord process occurs between days 15 and 17 .
The development of the notochord canal and the axial canal takes place between days 17 and 19 when the first three somites are formed .
The notochord process occurs between days 15 and 17 .