Fixatives & Pigment Chemistry
Excess calcium carbonate chips are added to the stock solution of this compound fixative to neutralize the formation of formic acid during storage
What is 10% Formal Saline?
Overly aggressive coarse trimming or facing of a paraffin block on the microtome causes this specific gouging artifact on the tissue face
What is a moth-hole artifact?
Distinct from skeletal muscle, smooth muscle fibers are non-striated, spindle-shaped, and contain a single centrally located nucleus with this characteristic shape
What is a cigar shape or elongated oval?
When labeling a specimen container in the receiving area, labels must always be adhered directly to the body of the container and NEVER to this part
What is the lid?
Tissues fixed in mercuric chloride contain extracellular black pigment deposits that must be removed prior to staining by treating sections sequentially with these two chemicals
What are iodine and sodium thiosulphate?
To prevent excessive ribbon distortion and wrinkles, floating-out water baths must be thermostatically maintained at a temperature this far below the melting point of the embedding wax
What is 5°C to 10°C below the melting point?
Seen as dark transverse lines between cardiac muscle cells, these specialized intercellular junctions facilitate coordinated wringing contractions of the heart
What are intercalated discs?
Tissues submitted without fixative from the operating room for STAT frozen sections or immunofluorescence studies are kept moist using this material
What is saline-soaked gauze?
Composed of picric acid, formalin, and glacial acetic acid, this intolerant fixative produces brilliant staining with acid dyes but leaves a yellow pigment and poses a major explosion hazard if allowed to dry completely.
What is Bouin’s Solution?
When floating paraffin ribbons on the water bath, this specific surface of the section must face down, and the trailing end of the ribbon must contact the water first to pull out folds
What is the shiny side (cut side)?
Characterized by unilocular cells where a single large fat droplet compresses the nucleus against the cell membrane, this tissue type presents a "hollow ring" appearance under H&E staining
What is White Adipose Tissue?
In a standard surgical accession number like S25-1 Part A, the "S" stands for surgical, "25" represents the year, and additional letter suffixes (A, B, C) serve this specific administrative purpose
What is linking multiple specimens from the same patient (or procedure)
Consisting of absolute ethyl alcohol, chloroform, and glacial acetic acid, this rapidly penetrating fixative preserves chromosomes and glycogen for urgent biopsies, but becomes severely intolerant after 4 hours
What is Carnoy’s Solution?
Formed when atmospheric oxygen oxidizes formalin to formic acid in blood-rich tissues, this microcrystalline, anisotropic artifact deposit is known by this chemical name
What is formal pigment, acid formaldehyde or hematein?
Lined by stratified epithelial cells with large rounded surface cells that flatten under pressure, this specialized epithelium is restricted to the urinary tract
What is Transitional Epithelium (Urothelium)?
To prevent tiny mucosal biopsies or cell fragments from being lost through cassette perforations during automated processing, tissue is placed inside paper, fine mesh, or between two of these items inside the cassette
What are sponges?
Unlike Zenker’s solution (which lyses red blood cells due to acetic acid), this mercuric chloride and potassium dichromate compound fixative uses formalin to preserve RBCs and is specifically recommended for bone marrow biopsies and demonstrating intercalated discs
What is Helly’s Solution?
The internal advance mechanism of a manual rotary microtome uses this mechanical system consisting of a notched wheel engaged by a pin to advance the specimen block per stroke
What is a ratchet-and-pawl system?
In hyaline cartilage, mature chondrocytes reside within these small cavities scattered throughout the firm, gel-like matrix
What are lacunae?
In cytology processing, non-gynecological liquid specimens are stained in a strict sequential order to prevent cross-contamination; this specific specimen type is always stained first
What is Cerebrospinal Fluid (CSF)?