THE PITUITARY BODY 



rather large (22-23 rnm.) larvae oi Rana temporaria by means 

 of a galvanocautery. Among 1,200 operated animals, 10 of 

 of the survivors failed to undergo metamorphosis. Three of 

 the operated tadpoles in which subsequently no anterior-lobe 

 cells could be demonstrated histologically, and 3 control 

 tadpoles, are shown in Figure 43. The striking associated 

 atrophy of an operated tadpole's thyroid in comparison with 

 that of a control tadpole is illustrated by the photomicro- 

 graphs of Figure 44. Adler also mentions an atrophy of the 



^mm. 



Fig. 44. — Photomicrographs of the thyroid glands of a normal control tadpole 

 (left) and a hypophysectomized tadpole (right). From Adler, Arch. Entw.-mech. 

 Organ., XXXIX (1914), 21-45. 



gonads of the operated animals. Two years later Smith and 

 Allen independently performed successful excision of the 

 anlage of the anterior pituitary in tadpoles about 4 mm. long, 

 and thus avoided serious injury of the mouth and brain so 

 common in Adler's series. All investigators agree that hypo- 

 physectomy in the tadpole prevents metamorphosis because 

 of the subsequent atrophy of the thyroid (Smith, 1916, 1920; 

 Allen, 1917-18, 1922, 1924-25; Smith and Smith, 1922; and 

 Magdalena, 1933). Smith and Smith found that the size of 

 the thyroid gland of the hypophysectomized tadpole was only 

 7-20 per cent of the normal. They also found clear-cut mi- 



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