Qiu Shudong

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HISTOLOGY
Qiu Shudong
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• INTRODUCTION
• Definition A science study normal
  micro-structure its related function of human
  body. 4 structural levels Cell the
  smallest structural functional unit.
  Tissue groups of cells (similar in morphology
  or related in function)intercellular materials
  4 types of fundamental tissue epithelium
  connective tissue muscular tissue
  nervous tissue

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Organs organizations of various kinds of
tissues in particular ways perform a specific
function. System formed by several
function-related organs which together perform a
continuous physiological function. For
example digestive system
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Why to study histology ?

• To complete the knowledge of human bodys
  structures----from gross to microscopic
• Be able to understand how the different tissues
  function----the basis of physiology
• Can find the diseases only after the normal is
  known----the basis of pathology
• It is related to some modern science fields cell
  apoptosis, cell recognition, implantation of
  embryo stem cells, eugenics and etc.
• It is also a foundation of clinic sciencesfor a
  good doctor needed in futrue

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• Unit used in microscope
• 1µm1/1000 mm
• 1 n m1/1000µm
• Maximum resolution
• Light microscope 0.2µm
• Transmission electron microscope 0.2nm
• Scanning electron microscope 5nm

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• Investigative methods of histology

I. Light microscopy
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• 1. Tissue preparation
• A. paraffin section preparation
• Specimen as fresh as possible
•  Fixation fixative formalin solution
• purpose to preserve the structural
• organisation
• Dehydration replace the water in the tissue
• by alcohol
• Clearing replace the alcohol by xylene
• Embedding replace the xylene w/ melted
• paraffin
• Sectioning mounting

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• B. Frozen section
• Better for preserving chemical components
• (e.g. enzymes)
• Freezing?cryotomy?staining
• C. the others
• Smear preparations
• for blood etc
• Grind preparations
• for bone

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• 2. Staining
• Purpose To make tissue section pigment
• for observation.
• H-E Staining
• Hematoxylin basic dye, purple-blue
• Eosin acid dye, pink color
• Basophilic components bonded by basic
• dye (H) pruple-blue(nuclear chromatin
• basophilic substance in cytoplasm)
• Acidophilic components bonded by acidic
• dye (E) pink (cytoplasm collagenous fiber)

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• Neutrophilic do not stain w/ both basic and
• acid dyes
• Metachromasia a dye stains tissue a
• different color from that of dye solution, e.g.
• toluidine blue stains mast cells in purple color
• Special staining
• Argyrophilia
• Fluorescent staining

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HO (Hoechst 33258)-PI staining shows the
apoptosis in human HL-60 cells
Silver staining of the neuron and the bile
canaliculi
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II. Electron Microscopy

• 1. Transmission Electron Microscope (TEM)
• Using a beam of electrons (short wave-lengths)
• instead of visible light.
• Section preparation
• similar to those for L.M mainly,
• plastic instead of paraffin,
• 50-70nm thick,
• heavy metal salts instead of HE.
•  Resolution 0.1-0.5nm (0.2nm)
• Ultrastructrue The structure in EM
• Electron-dense / electron-lucent

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Transmission Electron Microscope
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Diagrams of TEM
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• 2. Scanning Electron Microscope (SEM)
• Sowing the 3 dimensional surface
• Architecture of cells and tissues
•    Resolution 5nm

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III. Histochemistry Cytochemistry

• Reveal the chemical composition in situ
  (e.g. proteins, a.a., nucleic acid, lipids,
  enzymes etc.) w/ chemical, biochemical methods.
• The product of chemical reaction should be
  insoluble / colored / electron- scattering, be
  seen in LM or EM

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• For instance
• PAS(Periodic Acid Schiff) reaction
• for manifesting polysaccharide and
• proteoglycan (e.g. glycogen).

polysaccharide HIO4 (hydroxyl group)
(oxidise) Aldehyde group
Shiffs reagent (colorless)
Purplish red depositor
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PAS reaction in the hepatocytes
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Immunocytochemistry

• Based on antigen binds to specific
  antibody.
• Tissue section w/ Antigen labelled
  antibody
• labelled Ag-Ab
  complex

Fluoresceinlabelling
enzyme labelling
colloidal gold labelling
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NOS GnRH positive Neurons in hypothalamus of
rat
NOS positive neuron in hypothalamus of rat
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m-ATPase activity in skeletal muscles
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• IV. tissue culture
• V. isotopic tracing
• VI. in situ hybridization (ISH)
• nucleic acid molecular hybridization
  

Use nucleotide probe to check
target fragment of intracellular DNA or mRNA
in situ, in order to study the gene expression.
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Expression of PSA and PSAmRNA in human prostate
(histochemistry ISH)
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The method in learning histology

• Combination of the 2 dimentional structure with 3
  dimentional

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• Combination of the theory with
• practice
• Combination of the structure
• with function
• Concern the dynamic change