MAST CELLS IN PATHOLOGICAL CONDITIONS 



mice undergoing local treatment with a carcinogen. This is particularly evident 

 when the carcinogen is tar (Bierich, 1922; Dreifuss and Bloch, 1922; Peyron, 

 1923; Lipschiitz, 1924; Ulesco-Stroganowa, 1927, de Vinals, 1931). The mast- 

 cell content of the painted area steadily increases during the induction period 

 until, on occasion, the aggregates of mast cells become visible to the naked eye 

 (Borrel et al, 1923; Schreuss, 1923; Fabris, 1927; Twort and Twort, 1930). 

 That the mast-cell response is not merely part of a tar dermatosis is shown by 

 the development of a similar reaction following the infrequent application of 

 a pure carcinogenic hydrocarbon dissolved in benzene (Cramer and Simpson, 

 1944) or even in acetone (Orr, 1938). In seeking to evaluate the significance 

 of the mast-cell reaction in carcinogenesis in the skin of mice, it is of interest 

 that a mast-cell response has also been observed in the skin of rats subjected to 

 the action of arsenic or X-iays (Bierich, 1922) and in the skin of mouse or man 

 following exposure to ultra-violet light (Meirowsky, 1908; Von Mollendorf, 

 1928). It seems that at least in certain species the mast-cell response is in some 

 way related to the carcinogenic response, though the mechanism of the reaction 

 is not yet understood. 



To sum up. Later investigations on the mast cell in chronic inflammation 

 and in pathological conditions characterized by fibrosis endorse Ehrlich's 

 original belief that there is some functional association between the mast cell 

 and the connective tissue, especially at the stage of fibrillogenesis: many of the 

 observations on the occurrence of mast cells in and around established tumours 

 can also be explained in this way. Other tumours rich in mast cells yet poor 

 in fibrous tissue, and the curious local mastocytosis in the skin of mice during 

 carcinogenesis are not yet understood. 



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