GROWTH OF THE ENDOCRINE GLANDS AND VISCERA IN THE CHICK¹²

Abstract

THE GROWTH AND DEVELOPMENT of the White Leghorn chick from hatching until 30 days of age is very rapid as was shown in previous work, Breneman (1). It was suggested (2), that a secretion of gonadotrophic hormone by the pituitary and androgenic substance by the testes may begin as early as the fifteenth day after hatching. No analysis has been made, however, of the secretion ofother hormones nor of the development of the viscera during this period of rapid growth. The sensitivity of the Leghorn chick to slight variations in pituitary hormone level, as evidenced by testes growth or inhibition, and to varying amounts of androgenic hormones, as demonstrated by comb growth, makes this form especially valuable both as a test animal and for thestudy of normal development. It was hoped that the presence of pituitary thyrotrophic hormone might be detected because the thyroid gland of the chick is easily stimulated, Smelser (3).