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: In the intact male and female rat , no direct relationship was observed between dose of tetracycline and hepatic accumulation of triglyceride .
### Output Text:
In the intact male and female rat , no direct relationship was observed between dose of <span class="chemical">tetracycline</span> and hepatic accumulation of <span class="chemical">triglyceride</span> . 