Artifacts in Histological Preparations
Dec 19, 2015
Artifacts in Histological Preparations
Microwave heating
It’s a kind of low power energy carried by micro-waves
Internal direct heating is our advantage
It’s a physical effect, neither chemical nor magical
Perception Reality
Microwaves cook my samples Microwaves create physical heat like conventionals do, but internally in the tissues. Better homogenity & efficiency.
Rapid processing = poor morphology
Today’s technology makes 12-14 hours an inefficient use of time. Quality is guaranteed priority.
Antigens will be lost forever Diagnostic equivalence is validated by studies showing optimal antigen reactivity.
Molecular studies are not possible
Microwave do not affect DNA, RNA and proteins’ quality at all.
Day processing is useless Day processing = same day diagnosis = patient centric care
1.Samples Preparation
Artifacts
Heat Damage
Fig.1 Breast biopsy
Damage from laser-generated heat or over-heated wax or while drying slides:
• loss of nuclear and cytoplasmic detail
• connective tissue fibers become coagulated
Crush Artifact
Fig.2 Section of lymph node
Damage from crushing by forceps or other surgical instruments:
• darkly staining
• distorted cell nuclei
• some stretching and flattening of tissue
Postmortem Change
Fig.3 Section of liver
Autolysis for delay of fixation:
• poorly defined nuclei
• imprecise cytoplasmic staining
Specimen Marking Dyes
Fig.4 Skin biopsy
Excision margins marked with coloring agents:
• not natural color of the margins
• possible penetration into the tissue
2.FixationArtifacts
Zonal Fixation
Fig.5 Section of liver
Different degrees of fixation at different levels within the specimen:
• insufficient time in fixative
• specimen too large
• reagent with poor penetration rate
Streaming Artifact
Fig.6 Section of liver
Precipitation and displacement of glycogen by an advancing fixation front
Formalin Pigment
Fig.7 Red cells in a section of kidney
Reaction of non-buffered (pH acid) formalin with hemoglobin:
• pigment as a brown to black associated with red blood cells
Mercury Pigment
Fig.8 Section of kidney
Fixation in mercuric chloride-containing fixatives:
• random brown to black granular deposits
3.Tissue-ProcessingArtifacts
Vessel Shrinkage
Fig.9 Section of brain stem
Poor brain fixation:
• perivascular shrinkage
• membrane separation
Poor Processing
Fig.10 Breast specimen
Inadequate fixation, too short processing cycle, inappropriate or exhausted reagents, mechanical fault with the processor, wrong replacement of solvents:
• extensive loss of architectural detail and clarity
• disruption within loose connective tissue
Imcomplete Dehydration
Fig.11 Gastrointestinal biopsy
Incomplete dehydration during processing:
• loss of nuclei details
• cloudy appearance of sections
Under Decalcification
Fig.12 Section of bone
Inadequate decalcification:
• appearance of dark blue areas with hematoxylin in the trabeculae
Over Decalcification
Fig.13 Sections of bone
Excessive decalcification:
• loss of all nuclear detail
• distruction of tissue morphology
4.StainingArtifacts
Residual Wax
Fig.14 Section of skin
Incorrect dewaxing prevents solutions penetration:
• presence of areas totally absent of stain
Incomplete Staining
Fig.15 Section of liver
Inadequately filled staining dish:
• absence of stain in some area of the section
Nuclei Not Crisp
Fig.16 Section of skin
Incomplete fixation or residual water after dehydration:
• “smudgy” or not crisp nuclei
• no distinct chromatin patterns
Thanks