In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: After EE treatment , changes in immunostaining for 7H6 and ZO - 1 were similar to those seen in periportal hepatocytes after BDL , but distributed more diffusely throughout the lobule .
### Output Text:
After <span class="chemical">EE</span> treatment , changes in immunostaining for 7H6 and ZO - 1 were similar to those seen in periportal hepatocytes after BDL , but distributed more diffusely throughout the lobule . 