INTRO_TO_TISSUE_PROCESSING

Specimen Accessing

The process of assigning a unique identification number to a tissue specimen for tracking and management.

Fixation

The process of preserving tissue samples to maintain their morphological and chemical integrity.

Additive Fixation

A fixation method where the chemical constituent of the fixative becomes part of the tissue.

Non-additive Fixation

A fixation method where the fixing agent alters tissue composition without incorporating into it.

Dehydration

The process of removing water from tissue samples during preparation for microscopy.

Decalcification

A process used to remove calcium deposits from tissue samples, particularly hard tissues like bone.

Embedding

The process of placing processed tissue into a medium that solidifies to provide support for cutting.

Trichrome Staining

A type of staining used in histology to differentiate between different tissue types using three colors.

Hematoxylin & Eosin (H&E) Staining

A widely used staining technique that provides contrast to cellular and tissue structures.

Specimen Dissection

The process of carefully cutting and examining specimens in the laboratory.

Laboratory Safety

Protocols and practices designed to minimize risk and ensure the safety of laboratory personnel.

Secondary Fixation

The process of placing already fixed tissue into another fixative to enhance specimen quality.

Immunofluorescence

A technique that uses fluorescent antibodies to visualize specific proteins or antigens in tissue samples.

Chemical Fixatives

Substances used to preserve tissue by chemically altering or stabilizing cellular components.

Artifact Pigments

Unwanted coloration in tissue samples caused by improper fixation or processing methods.

Microwave Technique

A method used to accelerate tissue processing or staining by applying heat in a microwave.

Mordant

A substance used to enhance the staining of tissue, often acting as an intermediary between the dye and the substrate.

Tissue Fixation Timing

The period between specimen collection and fixation, crucial for preserving tissue quality.

Tissue Processing

The series of methods used to prepare tissue samples for microscopy, including fixation, dehydration, clearing, and embedding.

Clearing

The process of removing the dehydrating agent from tissue samples and replacing it with a medium that is compatible with embedding material.

Paraffin Embedding

A common embedding technique where tissues are encased in wax to facilitate thin sectioning for microscopy.

Tissue Sectioning

The process of cutting embedded tissue into thin slices for examination under a microscope.

Microtome

A device used to cut thin sections of tissue for microscopic analysis.

Staining Procedures

Various methods applied to tissue sections to enhance contrast and visualize specific structures or components.

Rehydration

The process of gradually replacing the clearing agent with water in tissue samples before staining.

Lipid Fixation

A technique in histology that preserves lipid structures within cells and tissues.

Cryostat Techniques

Methods that rapidly freeze tissues to allow preparation of thin sections for microscopic analysis.

Sudan Black and Oil Red O

Stains used in lipid fixation to visualize lipid structures in tissue samples.

Mercuric Chloride

A common fixative for lipids used in a 5-7% aqueous solution, but requires careful handling due to toxicity.

Potassium Dichromate

A fixative that stabilizes lipid molecules but is a carcinogen and must be handled with caution.

Cryostat Sectioning

A technique that facilitates rapid histological assessments on-site to inform treatment decisions.

Microscopy Applications

Visualization of preserved lipid structures using light microscopy or electron microscopy, depending on resolution needs.

Significance of Lipid Fixation

Crucial for studying metabolic disorders, obesity, and lipid metabolism conditions like diabetes and atherosclerosis.

Carbohydrate Fixation

Utilizes alcohol fixatives to denature proteins and precipitate carbohydrates, preserving glycogen and sugar structures.

Protein Fixation

A method used to preserve the structural integrity of proteins in tissue samples.

Neutral Buffered Formalin

A widely used fixative that maintains pH stability and prevents pigment formation.

Formol Saline

A combination of formaldehyde and saline effective in preserving cellular details while minimizing shrinkage.

Glycogen Fixation

A technique aimed at preserving glycogen structures within tissue samples.

Karnovsky’s Paraformaldehyde-Glutaraldehyde Solution

An aldehyde fixative mixture effective for electron cytochemistry, enhancing tissue preservation for microscopic analysis.

Acrolein

An aldehyde introduced as a mixture with glutaraldehyde or formaldehyde, useful in tissue fixation.

Formaldehyde (Formalin)

One of the most widely used fixatives, compatible with many stains; usual fixation time is 24 hours.

10% Formalin Saline

A fixative for CNS and post-mortem tissues, requiring a fixation duration of over 24 hours.

10% Neutral Buffered Formalin

Preferred for preserving surgical and research specimens, preventing pigment precipitation.

Formol-Corrosive (Formol-Sublimate)

Recommended for routine post-mortem tissues and effective for various staining procedures.

Alcoholic Formalin (Gendre’s Formalin)

A rapid fixative that can also dehydrate tissues, preserving glycogen and suitable for sputum fixation.

Glutaraldehyde

Used in concentrations of 2-5% for small tissue fragments and 4% for larger tissues; excellent for electron microscopy.