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: Light microscopy of renal biopsy samples showed minimal glomerular capillary wall thickening and mesangial matrix increase , or no departure from normal .
### Output Text:
Light microscopy of renal biopsy samples showed minimal glomerular capillary wall thickening and mesangial matrix increase , or no departure from normal . 