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: OBJECTIVES : To evaluate the morphologic changes in rat urothelium induced by indomethacin .
### Output Text:
OBJECTIVES : To evaluate the morphologic changes in rat urothelium induced by <span class="chemical">indomethacin</span> . 