CH13 - Histopathologic Techniques & Cytology

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Define “Histology”

Define “Histology”

The science that deals with the microscopic identification of individual cells and tissues. (microscopic anatomy)

Define “Pathology“

The science that deals with the study of the characteristics, causes, and effects of disease, as observed in the structure and function of the body. (Disease processes)

Define “Histo-Pathology“

The combined study of histology and pathology, and their relationship to each other.

Define a “Pathologist“

The medical doctor engaged in the practice of pathology.

May be surgical, clinical, or autopsy pathologist.

Define “Medical Lab Scientist/Histologic Technician“

The person concerned with the task of preparing specimens and performing lab tests.
In histopathology labs, they are responsible for preparing slides from surgical or autopsy material which is to be examined by the pathologist for diagnosis.

What are the two divisions of pathology?

1. Anatomical pathology

2. Clinical pathology

What are the two branches within anatomical pathology?

1. Surgical

2. Autopsy

The Surgical branch in anatomical pathology involves?

Biopsy; to remove tissue from a living body for diagnostic purposes

The Autopsy branch in anatomical pathology involves?

Examination of a corpse to determine/confirm cause of death, aka necropsy.

What is done in the Clinical Pathology division?

Various standardized procedures are performed in the laboratory on body fluids for the diagnosis of diseases.

What are the subdivisions in the clinical pathology division?

1. Hematology

2. Microbiology

3. Clinical Chemistry

4. Serology & Immunohematology

5. Clinical Microscopy

6. Parasitology

Define “etiology“

Cause of disease

Define “pathogenesis“

the process of the development of disease

Define “morphological changes“

cellular adaptations, cell injury, and cell necrosis

What are the classifications of diseases?

1. Congenital and Hereditary Diseases (birth defects)

2. Circulatory Disorders

3. Inflammation

4. Degenerative or Retrogressive Diseases

5. Metabolic Disturbances

6. Nutritional Deficiency States

7. Neoplasms

What is the FIRST step in general tissue processing?

Specimen collection.

What are the two phases of an autopsy?

1. Gross exam

2. Microscopic exam

What is the SECOND step in general tissue processing?

Gross examination; the study of the organs, parts, and structures of a body that are visible to the naked eye; aka Macroscopic Anatomy

What is the THIRD step in general tissue processing?

Fixation

What are the purposes for fixation? (3)

• Prevent decomposition and Autolysis

• Protect from putrefaction (decay/rot) and damage

• Render some tissues insoluble

What is decalcification?

• The process of removing calcium salts or lime salts and its deposits from hard tissues so that softening will take place to facilitate embedding and sectioning.

When is decalcification conducted?

After fixation on bones, teeth, atheromatous aorta, calcified tuberculous foci, and other calcified tissues.

What is the FOURTH step in general tissue processing?

Dehydration

What is the purposes for dehydration? (2)

1. Remove excess extracellular water

2. Introduce tissue to clearing agent

What is the FIFTH step in general tissue processing?

Clearing

What is the purposes for clearing?

1. Remove alcohol

2. Prepare for infiltration

What is the SIXTH step in general tissue processing?

Infiltration/Impregnation

• The process whereby the clearing agent is completely removed from the tissue and replaced by a medium that will completely fill all tissue cavities, giving a firm consistency to the specimen.

What is the SEVENTH step in general tissue processing?

Embedding

• The process where an impregnated tissue is placed into a precisely arranged position in a mold containing a medium which is then allowed to solidify thus allowing the specimen to be handled and fixed to the microtome block without damage to the actual tissue.

What is a microtome?

The machine/instrument designed for the actual cutting of thin sections of tissues.

What is the EIGHTH step in general tissue processing?

Sectioning

• Tissues are thinly and uniformly cut to facilitate studies under the microscope.

What is the NINTH step in general tissue processing?

Staining

What are the purposes of staining?

1. To render different tissue constituents more visible through color variation.

2. To promote easier optical differentiation for identification of cells and tissue components.

3. To display varying affinities of tissues and cells for most dyes.

4. Better study of physical characteristics and structural relationship of tissues and cells.

What is the TENTH step in general tissue processing?

Mounting

What are the purposes of mounting? (4)

1. Protection against bleaching or deterioration from oxidation

2. Preservation (of slides) for permanent keeping

3. Facilitate easy handling and storage

4. Prevention of section damage, which may lead to distortion during microscopic examination.

What is the ELEVENTH step in general tissue processing?

Labelling (the slide)

What is the TWELFTH step in general tissue processing?

Microscopic Examination (of the slide)

Define “Cytology“

Microscopic study of cells that have been shed, desquamated, or scraped off.

What are some common specimens in cytology?

• Vaginal scrapings/swabs

• Endocervical and endometrial scrapings

• Prostatic secretions

• Bronchial aspirate or sputum

• Serous fluids

• Gastric and duodenal fluids

• Cerebrospinal Fluid (CSF)

• Bone marrow aspirate

• Urine

Cytology is recommended for? (5)

1. Detection of malignant cells in the body

2. Detection of asymptomatic or precancerous lesions

3. Assessment of female hormonal status in case of sterility and endocrine disorders

4. Determination of genetic (phenotypic) sex

5. Detection of the presence of infectious microorganisms

What is Exfoliative Cytology done on?

Fluids.

What is the process of exfoliative cytology? (4)

• Refrigeration (1-10 C*)

• Centrifuge (Make a smear)

• Centrifuge (Cell block)

• Alcohol

What is Gynecologic Cytology done on?

Done on swabbed specimens; Pap smear

What is the process of gynecologic cytology? (5)

1. Fix slides with 95% ethyl alcohol

2. Air dry

3. Stain

4. Apply adhesive and cover slip

5. Etch glass for ID

What are the uses for the Routine Papanicolaou Staining Procedure?

Hematoxylin, Orange G6, and Eosin 36

What are the common stains for exfoliative cytology?

Papanicolaou stain, H&E, and Modified staining (Wright’s)