246 The Vertebrate Organ Systems 



The parathyrotropic factor seemingly regulates the increase of the 

 parathyroid gland cells. The interrelationships of the anterior lobe 

 and parathyroid gland have not been definitely established. 



Fig 74 —A pituitary dwarf and giant compared with two normal individuals. 

 (Courtesy Dr. Edmund E. Beard, from Anthony: Textbook of Anatomy and Physi- 

 ology, The C. V. Mosby Company.) 



The Function of the Lactogenic Hormone.— This hormone, 

 often known as prolactin, is very specific in its action, but operates 

 only after parturition. Further, it can initiate and maintain lactation 



