DISTRIBUTION OF GLYCOGEN IN THE BODY 321 



THE DISTRIBUTION OF GLYCOGEN IN THE BODY 



The presence of glycogen in tissues can be ascertained not 

 only by its isolation by chemical methods, but also by its 

 micro-chemical colour reaction, which depends on the deep brown 

 or violet colour which it gives with a watery solution of iodine. 

 By bringing microscopic sections of tissues in contact with such 

 a solution any glycogen which these may contain is at once 

 stained. In this way Barfurth ( 6 ) has examined a large number 

 of tissues and organs. 



In the liver, the amount of glycogen depends very largely 

 on the taking of food. This is very evident in the liver of 

 gastropods. After starvation for about three weeks all the 

 hepatic glycogen disappears in these animals, and it begins to 

 reappear in from nine to ten hours after food is taken. It has 

 been noticed that the glycogen is at first deposited in the con- 

 nective-tissue cells of the liver and afterwards in the epithelial 

 cells, just as in starvation it disappears first from the epithelial 

 cells and lastly from those of the connective-tissue. 



This glycogen is contained entirely in the extra-nuclear portion 

 of the cell ; none has ever, in any animal, been seen in the nucleus. 

 By its deposition the cells increase markedly in bulk and the 

 liver increases in weight. In the liver of many animals (e.g. 

 rabbit) the glycogen is deposited mostly towards the centre of the 

 lobule around the intra-lobular branches of the hepatic vein 

 the periphery of the lobule containing much less glycogen ; in other 

 animals, however, this distribution is not so evident. The different 

 lobes of the liver seem to contain the same amount of glycogen ; 

 in other words, the glycogen is evenly distributed throughout the 

 liver. The liver of a dog has been found to contain as much as 

 18-69 per cent, of glycogen (Schondorff). 1 



In the muscles of well-fed resting animals, glycogen is present 

 both in the sarco-substance and in the interfibrillary material 



1 Bernard and Barfurth state that the liver of embryos contains no glycogen 

 until the middle of foetal life, the other tissues being, however, more or less 

 rich in it. In the observations on which this statement is based, the glycogen 

 was merely extracted with boiling water, and no precautions were taken, that 

 the mother animal before slaughter had been normally fed. Pfliiger, by his 

 new method ( 6 ), has shown that glycogen is always present in the liver of foetal 

 calves, guinea-pigs, and lambs, at least during the first half of gestation. 



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