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: There were a significant dilatation of tubular lumens , extensive epithelial cell vacuolization , atrophy , desquamation , and necrosis in VCM - treated rats more than those of the control and the erdosteine groups .
### Output Text:
There were a significant dilatation of tubular lumens , extensive epithelial cell vacuolization , atrophy , desquamation , and necrosis in <span class="chemical">VCM</span> - treated rats more than those of the control and the <span class="chemical">erdosteine</span> groups . 