THE ENDOCRINE SYSTEM 



623 



luteinizing hormone (LH) and prolactin (lactogenic hormone). A num- 

 ber of other hormones have been postulated to be products of the 

 anterior lobe but their existence has not generally been confirmed. The 

 importance of these hormones is demonstrated by the marked abnormal- 

 ities which follow hypophysectomy: cessation of growth in young ani- 

 mals, regression of gonads and reproductive organs, and atrophy of the 

 thyroid and adrenal cortex (Fig. 30.9). 



Growth hormone was the first pituitary hormone to be described. 



Figure 30 8 Integumentary adaptations in normal frogs {Rana pipiens). A, Light- 

 adapted animal: B, dark-adapted animal. (Turner: General Endocrinology'.) C A 

 chromatophore, greatly magnified, showing the pigment. D, A section of skm of frog 

 adapted to a warm, light environment. E, Skin adapted to a cool, dark environment. 



