Introduction 



GUNNAR BlIX 



Medicinsk-kemiska Institutionen, Uppsala, Sweden 



In the present symposium problems related to polysaccharides occupy 

 a relatively modest place, being dealt with only at this afternoon's session. 

 This is perhaps a reasonable limitation in view of the general aim of the 

 symposium. But polysaccharides undoubtedly play a very important role 

 in "biological structures and functions" throughout the animal and plant 

 kingdoms down to the bacteria. Since the lectures we shall listen to during 

 the next few hours seem to be dealing mainly with metabolic and methodo- 

 logical aspects, it will perhaps be appropriate as an introduction to touch 

 upon the arrangement and functions of the polysaccharides in the tissues. 

 Because I have little personal experience of the conditions in plants I shall 

 confine myself to some words about polysaccharides in animal tissues. In 

 some regards they may have a wider application. 



Bone, cartilage, skin, tendons, blood vessels, etc., all contain con- 

 siderable amounts of acid mucopolysaccharides. As you know it has turned 

 out during later years that there are many kinds of these substances: 

 hyaluronic acid, chondroitin sulphuric acids of different types, kerato- 

 sulphuric acid and others. Within each species minor modifications 

 probably occur, at least as regards degree of polymerization. Certain 

 general statements may be made about the arrangement of the mucopoly- 

 saccharides in the structural pattern of the connective tissues, and also 

 about their physiological functions. They belong to the amorphous ground 

 substance, they are present in the form of a sol or a gel in the pores of a 

 collagenous network and thev are loosely or more firmly associated with 

 proteins. It also seems safe to say that they are in part responsible for the 

 physical, and not least the mechanical properties of the connective tissues. 

 But when we come to questions such as exact ultrastructural or molecular 

 arrangements and precise mode of functions we are still very much in the 

 dark. 



The physiological function of a biological substance is in the first 

 instance dependent on its chemical and physical properties. But these 

 properties may in difl^erent biological structures or environments have 

 very different physiological significance or consequences. 



I should like to illustrate this point with an example. Hyaluronic acid, 



