THE THYROID AND PARATHYROID GLANDS 795 



The results of experimental extirpation of the thyroid vary accord- 

 ing to the age of the animal, and frequently they are by no means 

 marked, provided sufficient parathyroid tissue has been undamaged. 

 The symptoms are in general thickening and drying of the skin, with a 

 tendency to adiposity and a loss of tone of the muscles. The body tem- 

 perature is low and the sexual functions become subnormal. Nervous 

 symptoms in the direction of mental dullness and lethargy are also 

 usually present. Surgical removal of the thyroid in man produces the 

 condition known as cachexia strumipriva. The symptoms may first of 

 all become apparent a few days after the operation, or they may remain 

 latent for years, and then develop so as to produce the condition known 

 as myxedema. When nervous symptoms are prominent in cachexia 

 strumipriva, it is usually taken as evidence that an excessive amount 

 of parathyroid tissue has been destroyed. Kocher states that after com- 

 plete loss of the thyroid, life is impossible for more than seven years, 

 and that to prevent ultimate ill effects, at least one-fourth of the organ 

 should be left intact. 



Disease of the Thyroid 



The symptoms of diseased conditions of the thyroid may be inter- 

 preted as the consequence of increased or diminished functioning of the 

 gland. Sometimes, however, the less active gland is really increased in 

 bulk, this increase being caused by the accumulation in it of very large 

 quantities of colloid material accompanied by an attenuated condition 

 of the vesicular cells (see page 793). When the gland is atrophied at 

 birth, the condition of cretinism soon becomes developed (Fig. 196). The 

 characteristic features of cretinism are: (1) An arrest of growth, espe- 

 cially of the skeleton, accompanied by incomplete ossification of the long 

 bones and a delay, often of several years, in the closure of the fontanelles. 

 The disturbance in growth of the long bones occurs along the epiphyseal 

 line, but the deposition of new bone beneath the periosteum proceeds, 

 more or less, normally. The consequence is that the bones increase in 

 thickness but fail to develop properly in length. (2) Poor development 

 of the muscular system. (3) An unhealthy, swollen condition of the skin, 

 so that it is yellowish in color, the face being pale and puffy. (4) An 

 abnormal development of the connective tissues causing a shapeless con- 

 dition of the surface; the abdomen is always swollen, the hands and 

 feet are shapeless, and the root of the nose depressed. (5) The nerv- 

 ous system also fail's to develop properly, so that at the age of puberty 

 or over, the child remains like an infant in his mental behavior, idiocy 

 being common. Indeed, the whole clinical picture is so character- 

 istic that once having seen a case no one can: fail afterward to 



