THE adrenal gland comprises virtually two distinct organs of separate embryologic origin, secreting chemical substances of two different categories: steroids and catecholamines. The cortex arises from the Wolffian duct and the medulla from the anlagen of sympathetic ganglia. The extensive effects of these two classes of hormones upon so many biological mechanisms in numerous organs and tissues render these endocrine glands a fruitful quarter for clinical investigation. Certain tissues may rely upon adrenal secretions for their own optimal function or they (and others, not necessarily primarily dependent upon these hormones) may be profoundly affected by excessive production of these humoral agents. During the past 20 years, practicable techniques have been developed and improved into accurate tools for the assessment of the operation of these structures.
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