basic histology and histological techniques (mls-hist 222
TRANSCRIPT
Basic Histology and Histological Techniques (MLS-HIST 222Histopathology department
L2:Methods of prepration of tissue and cells-15/12/2019Musa Omer Musa
Contact no 0912918273
The Aim of histology
• Histology is the study of tissues (from Greek.histos=tissue).
• Firstly: This involves the examination of the architecture and
relationship of the different types of tissue.
• Secondary: The detailed investigation of the structure of the
individual cells(cytology).
• By combining this knowledge of microscopic anatomy and
cellular composition much has been learnt about the
physiological function of tissues.
• The aim of histology is to is to obtain the greatest possible
amount of information from the tissue by various
histopathological techniques.
• Normal histology: Is the study of normal tissue and cellular
composition.
• Histopathology: Is the study of abnormal tissue and cellular
composition. Or the changes occurs to tissue morphology and
cellular details due to pathogen.
• Cytology: the study of normal individual cellular structure
• Cytopathology: the study of abnormal individual cellular
structure
Anatomy
Macro
Histology
Micro
cytology
• Histology:
• Normal histology General tissues: epithelial tissue,
connective tissue, muscular tissue and nervous tissue
• And systemic organs
• Pathology:
• General and systemic pathology
• Cytology:
• Gynecological cytology and non gynecological cytology
Methods of preparation of tissues and cells
• Can be classified into:
• 1.Prepration of fresh (living) tissues and cells.
• 2.Prepration of fixed (dead) tissues and cells
1.prepration of fresh (living) tissues and cells.
1. Preparation of Fresh cells and tissues
The demonstration and examination of tissues and cells in their
living state.
Can be sub divide into:
a. Direct examination.
b. Dissociation or teasing method.
c. Vital stain
a. Direct examination
• Cells are suspended in a fluid ,such as blood or lymph in a drop
of fluid
• .The fluid may required dilution with an isotonic solution such as
normal saline (0.85%).
• Then exam under microscope.
• Why isotonic solution?
b. Dissociation or teasing method
• Cells that are grouped together in a loose tissue as in
subcutaneous connective tissue may also be examined
directly if the tissue is thin .if the tissue is thick or in
case of a solid organ .cells can be separated from one
another in a fluid medium like normal saline(isotonic
solution).
C. The vital staining method
• The staining and demonstration of living tissues and cells
Can be sub divide into:
• I. Intra vital stain: the injection of a dye into the living
organism then examined by ultra sound also kuffer’s cell in liver
can be exam by the same way in which the cells engulf the
foreign body (vital stain) and takes the stain,
• II. Supra vital stain: staining the living cells of an organism out
side the body in vitro .
• These cells are dissociate in the staining solution.
• Example of vital stains Janous green , Indian ink and methylene
blue.
• Demonstrated cell like reticulocytes(RBCs) and cellular
structure like mitochondria.
• Nuclear is resistant to vital stain Explain?
• Vital stain is consider as cytoplasm stain?
Intra & supra vital stain
2.The preparation of fixed (dead ) tissues and cells
• Cab be divided into :
• Cytological preparation
• Sectional methods
• Cytological preparation :fluids containing cells or tiny fragments of tissue
such as aspirated bone marrow ,are smeared upon a microscope slide ,the
adherent cells fixed (killed) in order to preserve their appearance.
• The smear stained to demonstrate their structure (nuclear and cytoplasm
) structure ! ?. Finally mounted and examine under microscope .
• Cytological or smear preparation methods includes:
• Scrap method :(exfolative cytology) cells smear fixed in
95%ethanol stained then exam under microscopy.
• Crush method: impress tissue between two slides then smeared
fixed in 95%ethanol stained then exam under microscope.
• Impression method: done by touch the cut surface of soft
tissue cells adhere into the slide fixed in 95% ethanol stained and
exam under microscope useful in study of soft tumor rapidly.
• Body fluid: like CSF ,peritoneum ,pleural and fine needle
aspiration these fluids centrifuge smear sediment cells and tissue
fix in 95% ethanol then exam under microscopy
• It is preferred that to fix smear will it is wet in 95% ethanol.
Smear preparation
Sectional method
• These involve the cutting of specimen into a very thin translucent
slices or sections and have the advantages preserve the micro
anatomical relation ship of tissue to each other .section cut by
microtome which produce thin section 3-5 um in thickness.
• Sectioning method done after the following steps fixation in (10%
formalin) , processing , embedding then cutting or sectioning .
• After that sections are staining , mount and then exam under
microscope.
• Sectioning methods can be divide into:
• Embedded sectional method: in which embedding medium use to
support tissue to enable cut thin section by microtome the most widely
use embedding medium is paraffin wax others like , celloidine , gelatin,
water soluble wax , agar and resin.
• Non embedding sectional method: the tissue fluid use as
supporting medium after frozen the tissue example freezing
microtome and cryostat techniques.
Embedded and non embedded section
Different between smear and sectioning preparation
Smear preparation Sectional preparation
Lack micro anatomical relation ship
micro anatomical relation ship preserve
Two dimensional cellular structure
Three dimensional structure
Large ,flattened cells Small cells
Cellular details easily seen Cellular details not easily seen
Smear preparation include impression ,crush, scrap
Divide into embedded and non embedded
Easley and rapid in preparation Take long time and needs skills
Section & smear preparation
Methods of examination
• Macroscopic examination: naked eye examination
• Microscopic examination :light microscope ,electron
microscope transmission E.M and scanning E.M
Normal liverHistology Anatomy
PathologySection Gross
Macroscopic examination
Microscopic examination
THE END