ENDOCBINI GLANDS. [45 



Endocrine Glands as Links between Chbomob m 



QUAUTD 



When it is concluded that there are constitutional, genetic fad 

 for build, the validity of this conclusion is uo1 weakened by the kni 

 role of endocrine glands on metabolism and build. Thus the i 

 ments of recent years have emphasized the importance of the rdle thai 



the thyroid gland plays in growth and development. As Uhlenhuth 

 (1922, p. 182) says: "The ontogenetic development of the individual 

 is controlled by the thyroid hormone." Since in cretins the thyi 

 functions imperfectly or not at all, the differences between 

 development of a normal child and that of a cretin are supposed to 

 indicate the scope of the control by the thyroid hormone. In the 

 cretin, growth is slowed up almost to cessation. In the long bones 

 the centers of ossification develop slowly. "The epiphyses may be 

 absent many years after they are due to appear and then union with 

 the shafts of the long bones indefinitely delayed. Periosteal as well 

 as endochondral bone formation may be greatly reduced and delayed. 

 The cranial bones are thin, poorly ossified, and osteoporotic; mottling 

 is sometimes evident ontogenologically." .... Incomplete closure 

 of the fontanelles is very common (Janney, 1922, pp. 391, 392). The 

 genito-urinary system is undeveloped; the external genitalia remain 

 infantile. The brain shows defective convolutions and all parts of 

 the central nervous system show deficient development. Owing to 

 the fact that the long bones of the leg develop imperfectly, while the 

 chest may continue to enlarge, the build of the cretin is usually la 

 for his age. Thus, in general, the specific metabolic changes air 

 retarded. When the thyroid functions imperfectly after maturity the 

 victim puts on fat. The fat is usually distributed nearly uniformly 

 under all parts of the skin. One of Janney's cases weighed 212 poui 

 at 12 years. Some degree of hypothyroidism is doubtless responsible 

 for many of the "very fleshy" persons referred to in the preceding 

 pages. The frequent recurrence of obesity in a family i^ in accordai 

 with the tendency for hypothyroidism to recur in different meml 

 of a family; a tendency shown remarkably in Barrett's i 1919) family. 

 The hypophysis, especially its anterior lobe, is believed to exercise 

 an important control over differential metabolism and the resulting 

 form. The results of hyperfunctioning of the gland are vei \ enl 



from those of hyperfunctioning of the thyroid. An extraordins 

 enlargement of certain parts of the skeleton, especially of the 1 

 the skull, the hands, the feet, and the ribs, occurs. There is, indeed. 

 in growing persons a tendency to the production ^i giants. In 

 underfunctioning of the hypophysis before puberty an extraordini 

 obesity is apt to appear, known as dystrophic adiposo-geni talis; 

 because, the more the fat increases in amount the more tin tttJ 



