What type of glial cells myelinate axons in the brain and spinal cord?

If an individual complains of multiple physical symptoms that are vague and seem to affect several different body parts or systems all at the same time, with no evidence of a physical problem, he or she may be suffering from __________ disorder

a. fugue b. conversion c. somatization d. autistic

Which of the following problems would a child in the concrete operational period be most likely to solve incorrectly?

a. chemical combinations problem b. conservation of liquid quantity problem c. class inclusion problem d. three-mountains problem