408 - Multicellular Animals, Especially Man 



fractionated extract of the tissue) seems to 

 exceed the combined potencies of all the in- 

 dividual substances that have been isolated 

 from the extract. Also the whole cortin ex- 

 tract, prepared according to the best known 

 methods, shows very little influence upon the 

 sexual functions of the animal. 



In man, the commonest type of adrenal 

 cortex insufficiency is encountered in Addi- 

 son's disease, a tubercular infection localized 

 mainly in the cortex portion of the gland. 

 A hyperactivity of the cortex is encountered 

 in some cases of adrenal tumor. Such tumors, 

 although very rare, especially in males, are 

 apt to give rise to a conciition known as 

 adrenal virilism, which can appear at any 

 age. In boys the sex organs, except for the 

 testes, may approximate full size and ma- 

 turity at an age of 1 or 2 years, and simul- 

 taneously the hair, voice, and body muscula- 

 ture take on the characteristics of an adult 

 man. But even greater is the misfortune of 

 a girl or woman who develops adrenal viril- 

 ism. In this case, the bodily development is 

 all in a masculine direction, producing a 

 bearded face, deepened voice, and consider- 

 able muscularity. Simultaneously the ovaries, 

 uterus, and vagina begin to atrophy; but 

 the clitoris enlarges, assuming the propor- 

 tion of a penis. Such changes, in both male 

 and female subjects, are somewhat difficult 

 to interpret, although they may be due to a 

 great overproduction of cortical hormones, 

 some of which have distinct androgenic prop- 

 erties. All in all, therefore, many more data 

 are needed before the problem of adrenal 

 virilism can be clarified and brought under 

 control. 



THE ENDOCRINE FUNCTION OF THE 

 PANCREAS 



An endocrine function of the pancreas was 

 first suspected in 1892, when it was observed 

 that depancreati/ed dogs quickly develop 

 severe symptoms of a fairly common human 

 ailment, diabetes mellitus. However, no hor- 

 monal activity could be found in the pan- 



creas until 1922. Then an extract capable of 

 alleviating diabetes was prepared from pan- 

 creatic tissue, and in 1927, purified crystalline 

 insulin was finally isolated. Insulin proved to 

 be a protein compound that is digested by 

 the trypsin of the pancreas; and unless pre- 

 cautions are taken to inactivate the enzyme 

 before extracting the hormone, insulin can- 

 not be obtained from the pancreatic tissues. 



The main part of the pancreas consists of 

 the digestive tubules that form the pan- 

 creatic juice, but there are considerable 

 masses of endocrine tissue occupying the 

 spaces between the tubules (Fig. 22-7). This 

 tissue makes up the islands of Langerhans, 

 which secrete insulin directly into the blood 

 stream. In the embryo, the endocrine tissue 

 of the pancreas buds off from the digestive 

 tubules and loses all connection with the 

 duct svstem of the gland. 



Hypoinsulinism. Diabetes mellitus is a 

 severe and fairly prevalent malady that has 

 been recogni/ed since antiquity. Without 

 treatment, the diabetic displays great thirst, 

 excessive urination, a steady and unchecked 

 loss of weight, weakness, prostration, coma, 





ISLAND 

 LANGERHANS 



ALVEOLI 



Fig. 22-7. The pancreas is both an endocrine and an 

 exocrine gland. It internally secretes insulin from the 

 islands of Langerhans tissue and it externally secretes 

 pancreatic juice from the alveoli. 



