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: Renal lesions were analyzed in hematoxylin and eosin , periodic acid - Schiff , and Masson ' s trichrome stains .
### Output Text:
Renal lesions were analyzed in <span class="chemical">hematoxylin</span> and <span class="chemical">eosin</span> , periodic acid - Schiff , and Masson ' s trichrome stains . 