HLSC 2465U Study Guide - Fall 2018, Comprehensive Midterm Notes - Muscle, Microvillus, Epithelium
HLSC 2465U
MIDTERM EXAM
STUDY GUIDE
Fall 2018
A&P III
Histological Techniques Notes
Steps for glass slide tissue Specimen Preparation:
- Specimen collection, gross description, dissection
- Tissue Fixation and processing
o Dehydration
o Clearing
o Wax infiltration
- Embedding (paraffin wax)
- Block sectioning (microtome)
- Tissue staining and cover slipping
1. Specimen Collection and registering
- Received fresh or in a formalin container
- Given a unique accession number
2. Gross description and dissection
- Macroscopic examination, witnessing colour, texture, weight,
dimension
- Report on findings is dictated
- 3mm sections of tissue are placed into cassettes
3. Fixation
- Harden or preserve tissues to make it “likelife”
- Prevents autolysis and putrefaction
- Most common fixative is 10% neutral buffered formalin
- Denatures and crosslinks proteins for preventing decomposition
- 2 methods of fixation
o Physical (freezing, heat, microwaves)
o Chemical (fluid fixative, 10% neutral buffer formalin)
4. Tissue Processing
- Remove all water from the tissue and putting wax on the tissue
instead.
- further fixation in formalin, dehydration with alcohols, clearing
(remove alcohols) using xylol, and wax infiltration (paraffin wax)
I. Dehydration (using ethanol)
II. Clearing (xylene)
III. Wax infiltration (molten paraffin wax)
5. Paraffin Embedding
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find more resources at oneclass.com
A&P III
- Embeds tissue in medium (paraffin wax) and slice them into
thin sections using the microtome
- Embedding provides support so that tissue can be cut properly
- After, it is set on a cooling plate
6. Cutting (Sectioning)
- Microtome sections piece of tissue
- 4 to 5 micrometers in thickness
- Form a wax ribbon and is taken to a water bath then a hot air
oven to remove excess wax before staining
7. Staining
- Paraffin sections are on glass slides and stained with water
soluble stains
- Hematoxylin and Eosin are the most common
o H → Cells nucleus, nuclear material (basophilic), dark
purplish blue
o E→ pinkish red, orange. Stains cytoplasm and organelles
(acidophilic), CT, and muscle
I. Get rid of wax (dewax)
II. Staining process
III. Permanent prep (mount)
8. Mounting
- Tissue is dehydrated with alcohol and xylene to preserve it.
- Covered with a thin piece of glass to protect it.
- Manual or by automated machine
Definitions
Histology→ Microscopic study of form and structure of normal tissue
Pathology→ microscopic study of changes in disease tissues
Tissue→ building block of organs, group of cells carrying out a
specific function
Histotechnology→ preparation of tissues for microscopic examination
Biopsy→ Small piece of tissue removed from patient for examination
with microscope
Autolysis→ degradation of tissues by own enzymes (lysosomes)
Putrefaction→ decomposition of tissue by bacteria, fungi, or viruses
(gives off rotting flesh smell)
Microtomy→ The process of cutting tissues into very thin uniform
pieces
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Tissue fixation and processing: dehydration, clearing, wax infiltration. Tissue staining and cover slipping: specimen collection and registering. Received fresh or in a formalin container. Given a unique accession number: gross description and dissection. Macroscopic examination, witnessing colour, texture, weight, dimension. 3mm sections of tissue are placed into cassettes: fixation. Harden or preserve tissues to make it likelife . Most common fixative is 10% neutral buffered formalin. Denatures and crosslinks proteins for preventing decomposition. 2 methods of fixation: physical (freezing, heat, microwaves, chemical (fluid fixative, 10% neutral buffer formalin, tissue processing. Remove all water from the tissue and putting wax on the tissue instead. further fixation in formalin, dehydration with alcohols, clearing (remove alcohols) using xylol, and wax infiltration (paraffin wax: dehydration (using ethanol) Wax infiltration (molten paraffin wax: paraffin embedding. Embeds tissue in medium (paraffin wax) and slice them into thin sections using the microtome. Embedding provides support so that tissue can be cut properly.
