182 



Discussions 



of ACTH and TSH, there is considerable evidence that the feedback is at the level of 

 the pituitary, so apparently the mechanism involved in gonadotropin secretion is 

 dilTcrent. 



Dr. Harris and Dr. Critchlow have presented data from their laboratories 

 indicating that certain hypothalamic and limbic lesions are associated with precocious 

 puberty in female rats. The data are quite striking and consistent, but I must admit 

 that I am somewhat surprised at their inability to localize this response to a single 



Area common to 

 lesions in 8 rats 



Sagittal section 



Ventral view 



Fig. 6. 



portion of the hypothalamus. In my laboratory, Mr. Gellert has been working on 

 this problem for two years. Because true precocious puberty is properly defined as the 

 early onset of otherwise normal sexual cycles, we have produced lesions in various 

 parts of the brain in immature female rats, and then followed them and their controls 

 until all were cycling. By serially sectioning the brains, we have located the lesion in 

 each of the animals and then divided the animals into groups on the basis of common 

 areas of destruction. In Fig. 5, the mean age for vaginal opening and onset of first 

 estrus are shown for normal controls, animals with lesions in the anterior hypothalamus, 

 animals with lesions elsewhere in the brain, and animals with a common area of 



