Chapter XVI 

 MAST CELLS AND HISTAMINE IN THE SKIN 



(See Riley and West, A.M. A. Arch, dermatol., 19566) 

 MAST CELL-HISTAMINE k PROFILES ' IN NORMAL SKIN 



THE classical studies of Lewis (1927) and Dale (\929a and b) clearly 

 established the role of histamine in the reactions of the skin to injury. 

 It was thus of interest to examine the skin of various species and to deter- 

 mine the extent to which the distribution of the histamine in each is related to 

 the distribution of its mast cells. 



This study shows that at least so far as the skin of man, mouse, rat, cat, dog. 

 ox, pig, guinea pig, and rabbit is concerned, the bulk of the extractable histamine 

 is situated in that part of the skin which contains most mast cells. 



Histamine and mast cells in ears 



In the course of a survey of the development of mast cells in the skin of the 

 embryo, it was noted that the cells often appear first and are later extraordinarily 

 numerous in the ear. This finding was of particular interest in view of con- 

 temporary work by Feldberg and Miles (1953), who showed that the ear of 

 the guinea pig is comparatively rich in histamine. Histological studies con- 

 firmed that mast cells, though sparse in the skin of the guinea pig, are most 

 numerous in those regions in which Feldberg and Miles had obtained their 

 highest values for histamine — nipples, perivaginal skin, and the skin of the ear. 

 It was therefore decided to examine the ears of some of the larger domestic 

 animals in which a simple dissection of the tissues might suffice to indicate 

 which part of the ear contains the maximal concentrations of mast cells and of 

 histamine. 



Materials and methods. Whole ears of cattle and pigs obtained fresh 

 at the slaughter-house were split vertically down the midline, and representative 

 whole-thickness blocks for histology were removed from the base, centre and 

 tip. Next, the upper and lower skin coverings were freed from the intervening 

 cartilage by sharp dissection, and further samples of the various parts were 

 removed for histological examination. All tissue blocks were placed at once 

 in the fixative recommended for mast cells by Constantinides (1953) and were 

 later embedded in paraffin, cut at 8[j. and stained for mast cells with a 0-1 per 

 cent aqueous solution of toluidine blue. Other sections were stained by the 

 haematoxylin-eosin method for general histological detail. Mast cells were then 



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