White supremacy or white supremacism is a racist ideology centered upon the belief, and promotion of the belief, that white people are superior in certain characteristics, traits, and attributes to people of other racial backgrounds and that therefore white people should politically, economically and socially rule non-white people.
Neural tube defects occur when the bones of the spine do not correctly form, leaving the spinal cord and its nerves and coverings to protrude out through the skin (or lie just beneath it). The use of folate vitamins during pregnancy has decreased the incidence of neural tube defects.
The folding of the neural tube to form an actual tube does not occur all at once. Instead, it begins approximately at the level of the fourth somite at Carnegie stage 9 (around Embryonic day 20 in humans). The lateral edges of the neural plate touch in the midline and join together.