Chap. 15 



CHEMICAL REGULATION ENDOCRINE GLANDS 



275 



Fig. 15.17. Dwarfism accompanies extreme 

 underactivity of the pituitary (pars anterior) 

 beginning in childhood. The type of pituitary 

 dwarf shown in this figure has the proportions 

 of a normal, not unattractive person. He is 21 

 years of age. The man on the right is 5 feet, 7 

 inches tall. (From The Living Body, Copyright 

 1952 by Henry Holt and Company. Reprinted 

 with their permission.) 



the brain to the pars nervosa even though the pars nervosa itself is untouched. 

 And since* tumors in the hypothalamus result in abnormalities of growth, it 

 is probable that the pars anterior and hypothalamus are associated. The theory 

 concerning the role of the adrenal medulla under stress of excitement suggests 

 that the medulla is being controlled by the nervous system, but this is not 

 known. 



Functions of Endocrines in the Sex Organs 



In addition to producing eggs and sperm cells the ovaries and testes also 

 secrete hormones that aflfect allied structures and also secondary sex char- 

 acteristics such as voice, size, and coloration. Other endocrine glands, espe- 

 cially the thyroid and pituitary, also have a controlling influence on both 

 ovaries and testes. 



The antlers of male deer and the brighter colors of male birds are familiar 

 secondary sex characters. If the testes are removed (castration) from a young 

 deer, no antlers grow; a castrated cock has a small comb and a faulty crow 

 or none. In such animals the secondary sex characters are lacking, all repro- 



