18654
Immunohistochemically , doublecortin ( + ) cells were decreased at >= 20ppm in the subgranular zone ( SGZ ) of the dentate gyrus , and NeuN ( + ) - expressing mature neurons were decreased at 100ppm in the hilus on PND 21 .
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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:
 None