Spindle fibers are protein structures that form early in mitosis, or cell division. They consist of microtubules that originate from the centrioles, two wheel-shaped bodies located in the centromere area of the cell. The centromere is also known as the microtubule organizing center.
1 Night terrors are characterized by frequent recurrent episodes of intense crying and fear during sleep, with difficulty arousing the child. Night terrors are frightening episodes that disrupt family life.  A small percentage of children experience night terrors.
Night terrors happen less often than nightmares, and can sometimes seem like nightmares, but they are different in several ways. Night terrors do not happen during dreams. Night terrors usually happen in the early part of the night, often about 1 to 2 hours after the child has gone to sleep.