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: An increase in the volume density of secretory granules and a decrease in the volume densities of rough endoplasmic reticulum and microtubules was determined by morphometric analysis , suggesting that bromocriptine inhibits protein synthesis as well as bringing about a disturbance of the prolactin secretion .
### Output Text:
An increase in the volume density of secretory granules and a decrease in the volume densities of rough endoplasmic reticulum and microtubules was determined by morphometric analysis , suggesting that <span class="chemical">bromocriptine</span> inhibits protein synthesis as well as bringing about a disturbance of the prolactin secretion . 