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Fig. 9 





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Tissue spread, ox visceral pleura. The thin surface membrane contains numerous mast cells. (Riley 



and West (1953), J. Physiol. 120, 528.) 



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Fig. 10 



Vertical paraffin section, ox lung. Nearly all the mast cells are situated in, or immediately beneath, 

 the pleura; they are common in the adventitia of the small vessels with muscle coats and around 

 the lymphatics. Only a few are seen in the lung parenchyma. (Riley and West (1953), /. Physio/. 



120, 528.) 



