THE PITUITARY BODY 



and is recommended by Bergman and Turner), dilute acetic 

 acid or acidified acetone (Lyons, and McShan and French), 

 0.05 N NaOH (Evans). The further details of preparation 

 can be found in the reports of the various authors. 



McShan and French confirmed the statement of Bates and 

 Riddle that purified extracts withstand boiling in a solution 

 of pH 8. If the substance is a protein, this is a remarkable 

 property. So far, this experiment has not been performed 

 with crystalline hormone. In a solution at a lower or a higher 

 pH, the hormone is inactivated at a temperature of 100° C. 



SUMMARY 



The manner in which the anterior pituitary controls the 

 development of the breasts and the secretion of milk is more 

 complex than was suspected a few years ago. The important 

 and probably essential glands of internal secretion are the 

 pars glandularis of the pituitary body, the ovaries,^^ and the 

 cortex of the adrenal glands. 



For the growth and development of the breasts, an oestro- 

 gen analogous to what is obtained from ovarian tissue must 

 be secreted or injected. In some mammals like the guinea 

 pig this appears to be the only ovarian secretion required 

 for prelactation development. In other mammals like the 

 rabbit it is believed that corpus luteum hormone (proges- 

 terone) is also required later. However, development of the 

 breasts due to an oestrogen is prevented by hypophysectomy. 

 Also, there is other evidence that an anterior pituitary secre- 

 tion, which brings about development of the mammary 

 glands, is formed and liberated into the blood stream in re- 

 sponse to ovarian (or placental) secretion or to the injection 

 of an oestrogen. A working hypothesis regarding the growth 

 and development of the breasts is as follows: gonadotropic 

 hormones from the anterior pituitary are essential for the 



^"t For the purposes of this summary, breast development and lactation in male 

 animals will not be specifically considered. It may be mentioned that the develop- 

 ment of the rudimentary breasts of male animals appears to depend upon the testes 

 and the anterior pituitary. 



[172] 



