THE PITUITARY BODY 



ably purified thyrotropic hormone, which he used in large 

 doses, interrupted ovulation for as long as a month. All in- 

 vestigators agree that the gonad-stimulating principle of 

 pregnancy-urine has no effect on the bird's thyroid (Schock- 

 aert and Noether). This finding is similar to that in the mam- 

 mal. Ohnishi (1931) reported that anterior-lobe extract 

 caused an accumulation of colloid in the thyroid when ad- 

 ministered to chick embryos; but this observation, if con- 

 firmed, must be considered exceptional. 



The thyroid-pituitary interrelationship in mammals. — The 

 recognition of the fact that in mammals, as in amphibia and 

 birds, the thyroid is controlled by a thyroid-stimulating (thy- 

 rotropic) hormone secreted by the anterior lobe of the pitui- 

 tary is of great importance for the understanding of both nor- 

 mal and pathological secretion by the thyroid. Graves's dis- 

 ease and other disorders of thyroid secretion must be recon- 

 sidered from this new position.'' The experimental data re- 

 viewed below demonstrate that an internal secretion of the 

 anterior lobe is essential for the normal functioning of the 

 thyroid and that the administration of this anterior-lobe se- 

 cretion (as crude gland or extract) causes a marked increase 

 in the rate of thyroid secretion so that the condition of an 

 injected animal may, for a time at least, resemble Graves's 

 disease. Among the mammals from which experimental data 

 have been obtained are man, the dog, cat, sheep, guinea pig, 

 rabbit, rat, and mouse. 



The ejects of thyroidectomy. — Rogowitsch (1888, 1889) was 

 the first to observe the effects of thyroidectomy on the pitui- 

 tary of the dog and rabbit. He believed that he had obtained 

 histologic evidence of the vicarious formation of the thyroid 

 hormone (colloid) in the anterior pituitary, especially of the 

 rabbit, and explained the longer survival of the thyroidec- 

 tomized rabbit by the fact that the pituitary is relatively 

 larger in the rabbit than in the dog. In reality his dogs were 



^ For one interpretation, see Drouet (1934). 

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