Definition is a rhetorical mode that can be used in something smaller or shorter than a full paper. You can use extended definition for several paragraphs only in a paper of much greater length. You also can add to a paper a one-paragraph definition--like a brief encyclopedia definition.
Depending upon location, neural crest cells give rise to most of the peripheral nervous system, as well as various non-neural tissues, like craniofacial bone and cartilage, the thymus and parathyroid glands, and the cardiac outflow tract â in short, all of the tissues that are affected in DiGeorge syndrome.
Low parathyroid hormone levels can cause the blood calcium to be low. A number of conditions, such as DiGeorge syndrome, may cause low parathyroid hormone levels. Hypocalcemia is more common in premature and low birthweight babies. This is because their parathyroid glands are less mature.