19272
Moreover , where the 3D integrity of an EB is maintained , cytokines or drugs of interest to stimulate differentiation are often added directly to the culture medium at fixed concentrations and effects are usually limited to the outer layers of the EB .
 None
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