4843
To determine whether embryonic TCDD exposure inhibits epicardium and proepicardium ( PE ) development in zebrafish , we used histology and fluorescence immunocytochemistry to examine the epicardium formation in fish exposed to TCDD .
 Chemical: TCDD; Chemical: TCDD
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: TCDD, TCDD 
Answer:
 Chemical: TCDD; Chemical: TCDD