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: This study shows that prenatal dexamethasone in rats results in a reduction in glomerular number , glomerulosclerosis , and hypertension when administered at specific points during gestation .
### Output Text:
This study shows that prenatal <span class="chemical">dexamethasone</span> in rats results in a reduction in glomerular number , glomerulosclerosis , and hypertension when administered at specific points during gestation . 