fault in tissue processing

• RSN: Brittle or Hard tissues

  • Prolonged fixation
  • Prolonged dehydration
  • Prolonged clearing
  • Prolonged paraffin infiltration
  • Overheated paraffin oven
  • Drying out of tissue before actual fixation
• RMD: Brittle or Hard tissues


  Tissue may be softened by soaking in a small dish or bowl containing water with detergent, phenol or molliflex
• RSN: Clearing agent turns milky as soon as tissue is placed in it


  Water not completely removed due to incomplete dehydration
• RMD: Clearing agent turns milky as soon as tissue is placed in it


  Repeat dehydration with absolute alcohol then clear again
• RSN: On trimming, tissue smells of clearing agent


  Clearing agent not completely removed due to insufficient impregnation
• RMD: On trimming, tissue smells of clearing agent


  Block is trimmed down nearest to the tissue. Remaining wax is melted on embedding oven and paraffin impregnation is repeated, changing the paraffin at least once before blocking
• RSN: Tissue is opaque, section cutting is difficult due to presence of alcohol


  Insufficient clearing
• RMD: Tissue is opaque, section cutting is difficult due to presence of alcohol


  Repeat clearing; if object has already been embedded, prolong clearing up to 12 hours, then re-embed
• RSN: Tissue shrinks away from wax when trimmed

  • Insufficient dehydration therefore incomplete clearing and

  impregnation
• RMD: Tissue shrinks away from wax when trimmed


  Repeat the whole procedure
• RSN: Tissue is soft when block is trimmed

  • Incomplete fixation
• RMD: Tissue is soft when block is trimmed


  Repeat the whole procedure
• RSN: Airholes are found on tissue during trimming


  Incomplete impregnation
• RMD: Airholes are found on tissue during trimming


  Repeat impregnation
• RSN: On trimming wax appears crystalline

  • Contaminated wax 
  • Block not cooled rapidly enough
• RMD: On trimming wax appears crystalline


  Re-embed in freshly filtered wax
• RSN: Paraffin block, after cooling is moist and crumbles


  Insufficient paraffin impregnation
• RMD: Paraffin block, after cooling is moist and crumbles


  Repeat paraffin impregnation, then re-embed
• RSN: Inadequate processing of fatty tissues

  Routine schedule and reagents may not process fat adequately
• RMD: Inadequate processing of fatty tissues

  Fatty tissues should be sampled and cut thinly for easy reagent action. Ethanol is a poor fat solvent. To ensure complete dehydration, a far better lipid solvent (acetone or isopropanol) should be inserted before using the final absolute ethanol
• RSN: Hard, dense tissues 


  Tough keratin component of certain tissues
• RMD: Hard, dense tissues 


  Treat fixed tissues using 4% aqueous phenol for 24-72 hrs to soften
• RSN: On embedding, tissue is soft and mushy in the center


  Inadequate processing due to very thick or fatty sections
• RMD: On embedding, tissue is soft and mushy in the center


  At gross, cut thin sections especially fatty tissues, ensure complete fixation