GROWTH OF THE ENDOCRINE GLANDS AND VISCERA IN THE CHICK12

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Abstract
A study was made of the growth of White Leghorn and Rhode Island Red chicks from hatching until 30 days of age. Wts. were taken of body, comb, gonad, adrenal, thyroid, pancreas, liver, and intestines. Intestine length was measured. White Leghorn cockerels suffering from malnutrition were also studied. White Leghorns grew more rapidly than the Reds, and cockerels of both groups surpassed the pullets. Body wt. increased about 500% from the 5th to 30th day, but the Leghorn combs increased 20 times in proportion to body wt. at this time, with evidence of gonad stimulation and comb growth as early as the 10th day of age. Pullets showed much less comb growth and gonad stimulation and the responses were 5-10 days later. Adrenal glands remained rather uniform in relation to body wt. but the thyroids showed a relative decrease in size. Viscera had a maximum wt. at about 15 days. Comb and gonad growth was much slower and occurred later in the Rhode Island Reds. Wts. of other organs were similar to those of the Leghorns. Limitation of diet markedly decreased, but did not eliminate entirely, the secretion of the pituitary gonadotrophin. Comb growth increased about 6 times relative to body wts. and most of this growth took place during the 25-30 day interval. Adrenal glands were heavier, as were the thyroids also. Visceral wts. exceeded those of the controls in proportion to body wt.