GIG 



PHYSIOLOGY OF GONADS 



Cowie, FoUey, Malpress and Richarcl.son 

 (1952J,, and Meites and Sgouris (1954). 

 There is clear evidence that the estrogen- 

 progesterone combination acts at least 

 partly on the mammary parenchyma (Des- 

 clin, 1952; Meites and Sgouris, 1953) but 

 the mechanism of the action is unknown. 

 The hormonal interplay and complex endo- 

 crine interactions in the process of lactation 

 inhibition with estrogen has recently been 

 discussed at length by von Berswordt-Wall- 

 rabe (1958). 



Lactogenic effects of estrogens have al- 

 ready been mentioned; these have been 

 demonstrated most strikingly in cows and 

 goats, in which milk secretion has been in- 

 duced in udders being developed by exog- 

 enous estrogen. These experiments have 

 been reviewed in some detail by Folley and 

 Malpress (1948b) and Folley (1956).^ It is 

 generally assumed that estrogens act by 



stimulating the production of lactogenic and 

 galactopoietic factors by the anterior 

 pituitary. In experiments on the ovari- 

 ectomized goat we have shown (Cowie, 

 Folley, Malpress and Richardson, 1952; 

 Benson, Cowie, Cox, Flux and Folley, 1955) 

 that it is possible to select a daily dose of 

 estrogen which will induce mammary 

 growth but relatively little secretion in the 

 sense that the udder does not become tense 

 and distended as will happen when a lower 

 dose of estrogen is given — an observation we 

 may quote in support of the "double-thresh- 

 old" theory of estrogen action. The lacto- 

 genic effect of the lower dose of estrogen 

 could be abolished, however, by administer- 

 ing progesterone simultaneously with the 

 estrogen (Fig. 10.13), an observation in 

 accord with those of other workers on the 

 rabbit and rat (see above). 



In 1936 one of us (Folley, 1936) reported 



Fig. 10.13. Photographs of goat uddois dovelopcd by daily injections of hoxoostiol (HX) 

 with and without progesterone (PG). The hibels indicate the daily dose in mg. of each 

 substance. (Results from A. T. Cowie, S. J. Folley, F. H. Malpre.ss and K. C. Ricliardson, 

 J. Endocrinol., 8, 64-88, 1952.) 



