23448
Two reasons for this are that wild type mice have , in contrast to humans , a negligible number of mast cells localized in the smaller airways and in the parenchyma , and that only specific protocols show mast cell - dependent reactions .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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