Knowledge Base › Troubleshooting Atlas › Tissue processing
Dark or opaque tissue after processing
What it looks like
Tissue appears dark or opaque, lacking clarity and detail on the slide or block.
Where it usually appears: Typically observed in paraffin-embedded tissue sections after processing.
Likely causes
- Insufficient dehydration during processing
- Inadequate clearing of tissue
- Overheating during paraffin infiltration
- Poor quality paraffin used
- Improper fixation leading to tissue changes
Immediate checks
- Verify dehydration steps in processing
- Check clearing agent effectiveness
- Inspect temperature settings during paraffin infiltration
Corrective action
- Reprocess the tissue with proper dehydration
- Use fresh clearing agents
- Adjust paraffin infiltration temperature
Preventive action
- Ensure proper fixation techniques are followed
- Regularly calibrate processing equipment
- Use high-quality reagents and paraffin
This atlas is for educational purposes for laboratory professionals. It does not replace your institutional SOPs, manufacturer instructions, validated protocols or pathologist judgment. Adapt any action to your laboratory and equipment.
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