THE PITUITARY BODY 



therefore, the action of the lactogenic hormone do not de- 

 pend on the normal secretion of thyroid hormone to any im- 

 portant extent. Schooley, Riddle, and Bates (1937) were 

 able to produce a typical crop-gland response to lactogenic 

 hormone in a thyroidectomized pigeon. In mammals like the 

 dog, guinea pig, and rat, lactation following parturition or 

 the withdrawal of oestrin or the injection of anterior pitui- 

 tary extract is not prevented by thyroidectomy (Houssay, 

 1935; Nelson and Tobin, 1937). Likewise the development 

 of the breasts during pregnancy is not significantly inhibited 

 by thyroidectomy in the rat (Nelson and Tobin, 1937). Un- 

 like adrenal cortical extract, thyroid extract or thyroxine ad- 

 ministered coincidently with lactogenic extract will not ini- 

 tiate lactation in suitable hypophysectomized animals (Go- 

 mez and Turner, 1937; Nelson and Tobin, 1937). 



De Fremery (1936) reported that doses of thyroxine suffi- 

 cient to cause a severe hyperthyroidism (15 mg. daily) in 

 goats brought about a reduction in the volume of milk se- 

 creted daily. No change in the composition of the milk was 

 noted. After the administration of thyroxine was stopped, the 

 output was not restored to its original level. Van Tongeren 

 (1936) could demonstrate no action of thyroxine in lactating 

 women. Probably the doses he used were too small. 



Miscellaneous observations. — Additional evidence in favor 

 of the view that broody behavior of fowls depends upon the 

 lactogenic hormone has been gathered by Burrows and 

 Byerly (1936). The authors compared the proliferative 

 changes in the crop-glands of pigeons by implanting one pi- 

 tuitary (e.g., from a broody hen) over one crop-gland and the 

 other (e.g., from a laying hen) over the other crop-gland. 



action of lactogenic extract is not prevented by thyroidectomy. Riddle, Dotti, and 

 Smith suggest that a moderate increase (about 20 per cent) in the blood-sugar con- 

 centration as well as a calorigenic effect are caused by an action of lactogenic 

 hormone on adrenal cortical tissue. 



The concentration of sugar in the blood of the normal rabbit or of the normal 

 or depancreatized monkey is not affected by the injection of lactogenic extract 

 (Nelson, Turner, and Overholser, 1935). 



f 166I 



