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: Hypertension was observed in animals that had a reduction in glomeruli as well as in a group that did not have a reduction in glomerular number , suggesting that a reduction in glomerular number is not the sole cause for the development of hypertension .
### Output Text:
Hypertension was observed in animals that had a reduction in glomeruli as well as in a group that did not have a reduction in glomerular number , suggesting that a reduction in glomerular number is not the sole cause for the development of hypertension . 