MAST CELLS AND HISTAMINE IN SKIN 



given tissue and the density of its mast-cell population. This becomes more 

 apparent when the skin elsewhere is examined. 



Histamine and mast cells in abdominal skin 



As Table XXIV indicates, it was found possible to subdivide whole skin 

 from the base of the upper surface of ox ear into two parts, an inner and an 

 outer layer. Here it was observed that both mast cells and histamine are 



*3 r r y >\\ 





'S«* 



O. 





C 



Fig. 57 



Vertical section cat skin. Toluidine blue ( 144). The majority 



of the mast cells are small and lie close under the epidermis. Both 



they and the histamine remain behind when the dermis is scraped off 



at the level of the arrows. 



concentrated mainly in the inner, or dermal, layer. This suggested that it might 

 be feasible to examine the skin of other species in this way, scraping off as 

 much as possible of the dermis and examining it and the remaining upper layer 

 separately for mast cells and histamine. Since the method is essentially 

 comparative, each portion serves as a control for the other. 



Materials and methods. Samples of fresh abdominal skin from guinea pig, 

 rabbit, dog, cat, mouse, and rat were pinned out on a board, fur side down, 

 and as much as possible of the dermis was scraped off with a scalpel. Human 

 skin, obtained fresh at operation from mastectomy specimens, was subdivided 

 in the same way. Tissue spreads were made from the inner, or dermal, layer, 

 and paraffin sections from the remaining outer layer, which consists of epidermis 



147 



