Histopathology: Chapter 9 - Impregnation and Embedding

• Process by which the tissue is arranged in precise positions in the mold during embedding

  Orientation
• Plastic (Resin) Embedding is classified into:

  Epoxy, Polyester, & Acrylic
• -It is water soluble, hence does not require dehydration and clearing;-Used as an embedding medium for delicate specimen;-Also used in frozen sections

  Gelatin
• Impregnation method that is rarely used except when dehydration is to be avoided; and when tissues are subjected to histochemical and enzyme studies

  Gelatin Impregnation
• -another form of celloidin soluble in equal concentration of ether and alcohol-more explosive than celloidin

  Low Viscosity Nitrocellulose
• Celloidin impregnation method that is recommended for processing of whole eye sections

  Dry Celloidin Method
• How long should the tissue be impregnated in Wet Celloidin Method?

  5-7days
• Celloidin impregnation method that is recommended for bones, teeth, large brain section, and whole organs

  Wet Celloidin Method
• Two methods for Celloidin impregnation

  Wet Celloidin Method & Dry Celloidin Method
• Suitable for:-Specimens with large hollow cavities which tends to collapse;-For hard dense tissue such as bones and teeth;-And for large tissue sections of the whole embryo

  Celloidin
• Celloidin is also known as


  Collodion
• Purified form of nitrocellulose

  Celloidin
• Soluble and miscible in water; hence does not require dehydration and clearing


  Carbowax
• Most commonly used water soluble wax

  Carbowax
• Melting point of water soluble waxes

  38-42C or 45-56C
• -Not soluble in water, but is soluble in 95% Ethyl Alcohol-Can be used for impregnation without prior clearing and dehydration

  Ester wax
• Plastic polymers, mostly polyethylene glycols


  Water soluble waxes
• Melting point of Ester Wax

  46-48C
• Has a lower melting point but is harder than paraffin

  Ester wax
• - product of paraffin, containing rubber, with the same property as paraplast

  Tissue mat
• Less brittle and less compressible than paraplast

  Embeddol
• Permits large dense tissue blocks such as bones and brain to be cut easily

  Paraplast
• Recommended for embedding eyes

  Bioloid
• More elastic and resilient than paraffin wax

  Paraplast
• Melting point of Embeddol

  56-58C
• Synthetic wax substitute similar to Paraplast

  Embeddol
• Melting point of Paraplast

  56-57C
• Mixture of highly purified paraffin and synthetic plastic polymers

  Paraplast
• The tissue should not be left at the paraffin oven for more than ____

  4hours
• The traditional advice with paraffin wax is to heat the oven _____C to _____C higher than its melting point

  2C to 5C
• Overheated paraffin wax makes the specimen __________.

  brittle
• The paraffin oven or incubator should be regulated at what temperature?

  55 to 60 Degrees Celsius
• It is a polycrystalline mixture of solid hydrocarbons produced during the refining of coal and mineral oil

  Paraffin wax
• Melting point of paraffin wax

  55-60C upto 70C
• Infiltrating/embedding that is not recommended to use in fatty tissues

  Paraffin wax
• Simplest, most common, and the BEST infiltrating/embedding media

  Paraffin wax
• Types of tissue impregnation and embedding media

  Paraffin-wax, Celloidin/Collodion, Gelatin, & Plastic
• Process of replacing the clearing agent with a medium that fills tissue cavities

  Impregnation
• Embedding is also known as

  Casting or Blocking
• Impregnation is also known as

  Infiltration