ASCP HT study guide
ASCP HT · Work through your exam, one topic at a time.
The Histotechnologist (HT) credential is a professional certification for laboratory personnel who prepare tissue for microscopic examination - from specimen accessioning and fixation through processing, embedding, microtomy, routine hematoxylin and eosin staining, special stains, immunohistochemistry, and the quality and safety systems that surround that work. Candidates are typically histology technicians or technologists with bench experience who want formal recognition of their technical competence, and students completing an accredited histotechnology program who are preparing to enter the field. The ASCP HT study guide has 5 sections and about 1,443 words.
01Specimen Procurement, Handling, and Fixation
Fixation preserves morphology by cross-linking proteins (formalin) and inactivating autolytic enzymes, preventing autolysis and putrefaction. The variables that determine adequacy are fixative type, concentration, pH, osmolality, temperature, time, tissue thickness, and volume ratio.
304 words, about 2 min02Processing, Embedding, and Microtomy
Processing removes water and replaces it with paraffin: graded ethanol dehydration, xylene clearing (miscible with both alcohol and paraffin), then paraffin infiltration, often under vacuum and heat. Fatty tissue needs longer processing; dense fibrotic tissue also resists infiltration.
323 words, about 2 min03Routine (H&E) and Special Staining
Hematoxylin is a basic dye that binds acidic nucleic acids, staining nuclei blue-purple; eosin is an acidic dye that binds basic proteins, staining cytoplasm, collagen, and red cells pink. Progressive hematoxylin (Gill, Mayer) needs no differentiation; regressive hematoxylin (Harris) requires acid-alcohol differentiation followed by bluing in ammonia water, lithium carbonate, or Scott's tap water.
258 words, about 1 min04Immunohistochemistry and Molecular Techniques
Immunohistochemistry uses antibodies to detect antigens; molecular methods detect nucleic acids. Preanalytical variables dominate results: cold ischemia, fixation type and duration, and processing.
266 words, about 1 min05Laboratory Operations, Quality Assurance, and Safety
Laboratory operations rest on written SOPs, document control, competency assessment, proficiency testing, and accreditation requirements (CLIA, CAP). Quality assurance is the overall program; quality control is the day-to-day testing of reagents, equipment, and stains.
292 words, about 1 min