ARTERIES. 



125 



siderable size can be obtained. These 

 trated appearance, clear unstainable 

 throughout. They are due to the fact 

 made up of three layers, of which the 

 with magenta, and the other two not. 

 middle layer is absent. As described 



FIG. 89. 



have a peculiar fenes- 

 areas being present 



that the membrane is 



middle can be stained 

 At the feriestra the 



above, the individual 



Elastica interim 



^Endothelial layer 



-Elastic fibres 



Media 



I Bundles of smooth 

 I muscle cells 



.-Elastica externa 



Adventitia 



;_ .. \'ns vasis 



Part of a cross-section of the femoral artery of a dog. X 150. 



elastic fibres consist of a central stainable part and a capsule 

 which does not take up the dye. By the fusion of many of these 

 fibres the membrane with three coats is formed, the two outer 

 coats corresponding with the capsules of the fibres (Mall). 



The media consists of circular layers of smooth muscle 

 fibres, and the adventitia is made up of connective tissue. 



A medium-sized artery (Fig. 89) is composed of three dis- 



