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: When compared with the control group , both indomethacin groups revealed statistically increased numbers of mast cells in the mucosa ( P < 0 . 0001 ) and penetration of lanthanum nitrate through intercellular areas of the epithelium .
### Output Text:
When compared with the control group , both <span class="chemical">indomethacin</span> groups revealed statistically increased numbers of mast cells in the mucosa ( P < 0 . 0001 ) and penetration of <span class="chemical">lanthanum nitrate</span> through intercellular areas of the epithelium . 