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: In this study , we investigated the therapeutic potential of bone marrow mononuclear cells ( BMCs ) in a model of epilepsy induced by pilocarpine in rats .
### Output Text:
In this study , we investigated the therapeutic potential of bone marrow mononuclear cells ( BMCs ) in a model of epilepsy induced by <span class="chemical">pilocarpine</span> in rats . 