Growth inhibition in the skin induced by parenteral administration of adrenocorticotrophin.

For a number of years the anterior hypophysis has been known to play an important r61e in the regulation of body growth. I n general, the effects of hypophyseal secretions on growth have been found to be of a stimulative character. The growth stimulating or inhibiting action of such hormones is demonstrated most precisely by the changes they elicit in those tissues which normally undergo the most rapid cell division. Hair is such a rapidly growing structure and its growth has been shown to be affected by the anterior hypophysis. For example, Smith ('30) demonstrated in the rat that pituitary activity is essential to the normal maturation of hair from the infantile to the adult type. Apparently the growth hormone is primarily responsible for this effect (Thonipson and Gaiser, '32). Microscopically, hypophysw tomy of young rats has been found to cause a general atrophy of the skin with reduction in size of connective tissue fibers, hair follicles and their papillae (Snow and Whitehead, '35). Thesc changes were reversed by treatment of hypophpsectoinized rats with extracts containing the growth hormone. The general conclusion to be drawn from these early experiments