IMPREGNATION/INFILTRATION Flashcards
Process whereby the clearing agent is completely removed from the tissue and replaced by a medium that will completely fill all the tissue cavities, thereby giving a firm consistency to the specimen, and allowing easier handling and cutting of suitably thin sections without any damage or distortion to the tissue and its cellular components
IMPREGNATION
SIMPLEST, MOST COMMON AND BEST EMBEDDING MEDIUM
Paraffin wax
Tissue:Infiltrating medium ratio
1:25
Melting point of Paraffin wax
55-60°C
3 ways by which paraffin wax impregnation and embedding of tissues may be performed
Manual Processing
Automatic Processing
Vacuum Embedding
Paraffin wax requires at least ____ changes of melted wax at ____ intervals to ensure complete removal of clearing agent from the tissue; tissue is immersed in another solution of melted wax for approximately ____ to ensure complete embedding of tissue
4
15 minutes
3 hours
Automatic tissue processing machine
Autotechnicon
Processes done by the automatic tissue processor
Fixation
Dehydration
Clearing
Infiltration
Involves wax impregnation under negative atmospheric pressure inside an embedding oven to hasten removal of air bubbles and clearing agent from the tissue block, promoting a more rapid wax penetration of tissue
Vacuum Embedding
Recommended for urgent biopsies, for dense and hard fibrous tissues, for lungs, spleen, and other delicate tissues
Vacuum Embedding
Total impregnation time depends on:
Nature and size of the tissue
Type of clearing agent used
Substitutes for Paraffin Wax
Paraplast
Ester wax
Water soluble waxes
Mixture of highly purified paraffin and synthetic plastic polymers
Paraplast
Melting point of Paraplast
56-57°C
Has a lower melting point (46-48°C) but is harder than paraffin
Ester wax
Mostly polyethylene glycols with melting points of 38-42°C or 45-56°C
Water soluble waxes
Most commonly used Water soluble waxes
Carbowax
Purified form of nitrocellulose. Specimens with large hollow-cavities which tends to collapse (e.g., eyes), for hard and dense tissues (e.g., bones, teeth), and for large tissue sections of the whole embryo
Celloidin (Collodion)
2 methods of Celloidin impregnation
Wet celloidin method
Dry celloidin method
Recommended for bones, teeth, large brain sections, and whole organs
Wet celloidin method
Referred for processing of whole eye sections
Dry celloidin method
Rarely used except when dehydration is to be avoided and when tissues are to be subjected to histochemical and enzyme studies
GELATIN IMPREGNATION
Eyes
Bioloid
