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Histology self-study cards

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List the 9 steps of the paraffin technique
1- Obtaining of the tissue.
2- Fixation.
3- Dehydration.
4- Clearing.
5- Impregnation.
6- Embedding.
7- Sectioning.
8- Staining.
9- Mounting.
What are the advantages of paraffin technique?
1- It gives thin sections.
2- The sections are easily stained.
3- It gives serial sections.
What are the disadvantages of the paraffin technique?
1- The heat and chemicals may damage the tissue.
2- Fat is dissolved.
3- Most enzymes are inactivated.
What is the difference in the size of the tissue sample between E/M & L/M
L/M: Small pieces. 1cm3
E/M: Very small pieces: 1mm
What do we use in fixation when we're preparing a tissue sample?
L/M: Formol-saline
E/M: Glutaraldehyde 2.5% in 0.1M phosphate buffer and Osmium tetroxide 1% in the same buffer.
What do we use in dehydrating the tissue sample.
L/M: Ascending grades of Alcohol.
E/M: Ascending grades of Alcohol or Acetone.
What do we use in clearing?
L/M: Xylene or Benzene.
E/M: Propylene oxide.
what do we use in impregnation & embedding?
L/M: Paraffin or Paraplast
E/M: Hard media as epon and araldite.
What do we use to section the embedded tissue sample?
L/M: Microtome (5-8 micrometer)
E/M: ultramicrotome (50-100 nm)
Name the microscopes that can be used to study living cells:
1- Phase contrast.
2- Dark field microscopy.
3- Oblique illumination.
4- Bright field.
What are the difference between L/M and E/M:
L/M:
1- Light rays are used.
2- Mirrors and lenses are used.
3- It gives colored pictures.
4- It has a limited power of magnification.
E/M:
1- Electron beams are used.
2- Electromagnetic fields are used.
3- It gives black and white pictures.
4- It has a very high power of magnification.
How does the Hematoxylin Eosin stain works?
Hx stains the basophilic structures such as DNA & RNA blue.
Eosin stains Acidophilic structures red.
Silver stain is used for:
1- Retucular fibers.
2- Golgi apparatus.
3- Nerve cells and fibers.
The silver stain gives the structures it stains what colors?
Brown to black
What is the PAS stain used for?
It is used to stain carbohydrates and glycoproteins.
PAS gives the structures it stains a ... color
purple
What can we stain with PAS?
1- Mucus of goblet cells.
2- Brush border of absorbative cells.
3- Glycocalyx.
4- Basement membrane.
Sudan III is used to stain .... and it gives them a(n) .... color
Lipids, Orange color
What can we use to stain lipids?
1- Sudan III. (Orange)
2- Sudan black. (Black)
3- Osmium tetroxide. (Blue)
Metachromasia is:
Change in the color of the used stain as it combines chemically with the biological structures within the cells.
Give an example of Metachromasy:
1- Mast cells stained with toluidine blue, the cytoplasmic granules are stained reddish blue.
Give an example of vital(in vivo) staining
Macrophages stained with trypan blue or indian ink
Give 2 examples of supravital staining
1- Reticulocytes with Brilliant cresyl blue.
2- Mitochondria with Janus green B.
Peroxidase is used for labelling
antibodies
The Interphase is
The stage in the cell cycle at which the cell is not dividing.
Functions of the nucleus are:
1- Preservation of the genetic material.
2- Direction of the formation of certain proteins of the cell.
What is the structure of the Interphase nucleus?
1- Nuclear membrane.
2- Chromatin.
3- Nucleolus.
4- Nuclear sap.
How does the nuclear membrane appear under the E/M and L/M?
L/M: Single basophilic line.
E/M: 2 membranes each 8nm in thickness, separated by a 20nm perinuclear space.
What are the fibrous lamina?
A thin layer formed of filamentous material to which clumps of nuclear chromatin are attached.
What is the diameter of the nuclear pores?
40-100 nm
What closes the nuclear pores?
a thin pore diaphragm
What's the diameter of the central channel of the complex of the nuclear pores?
10 nm
Describe how Chromatin appears under the E/M and the L/M:
L/M: basophilic granules.
E/M: 2 types:
1- Condensed(heterochromatin, inactive).(constitutive and faculative)
2- Extended chromatin.
What's a nucleosome?
Looping and coiling of the DNA, it equals a central core of 2 histones and DNA which is coiled around that core by 2.5 turns
How does the nucleolus appear under the L/M?
1 or more rounded basophilic(RNA, nucleolus associated chromatin) bodies
What's the size of the nucleolus?
1 micrometer or more
What does the nucleolus consist of?
5% DNA, Little RNA, A lot of proteins
How does the nucleus look like under the E/M?
Dark material:
1- Pars fibrosa.(site of RNA synthesis)
2- Pars granulosa.(ribosomes)
What's the diameter of pars granulosa?
12-15 nm
What's the diameter of the pars fibrosa?
5 nm
What does the less dense material in the nucleolus consist of?
Chromosomal loops(10 nm)
Amorphous matrix made of proteins.
Which cells have different number of nucleoli?
1- Mononucleated cells. e.g. nerve cells
2- Binucleated cells, e.g, liver cells, Zona fasiculata of adrenal gland, top layer of tranditional epithelium.
3- Multinucleated cells, e.g, osteoclasts.
The nucleus is basal in the
columnar epithelium
What is the type of the nucleus of the lymphocytes?
Condensed
What are the organoids?
living contents of the cytoplasm which are essential for life,
What are the membranous organelles?
1- Cell membrane.
2- Mitochondria.
3- Endoplasmic reticulum.
4- Golgi apparatus.
5- Lysosomes.
6- Peroxisomes.
What are the non-membranous organoids?
1- Ribosomes.
2- Microtubules.
3- Centrioles.
4- Cilia & flagella.
5- Microfilaments.
What are the cytoplasmic inclusions?
1- Stored food.
2- Pigment.
3- Crystals.
Why can we see the cell boundary under the L/M?
1- Due to artifacts.
2- The obliquity of sections.
3- Condensation of the stain.
What's the diameter of the cell membrane?
8-10 nm
Why are cholesterol molecules found on the inner half of the cell membrane?
because they increase the stability and stiffness of the cell membrane
How can we stain mitochondria?
a- Iron HX.
2- Supravital, Janus Green B.
What's the size of the mitochondria?
0.1-0.5 micrometer in width
up to 10 micrometers in length
What are the sizes of lysosomes?
0.2-0.4 micrometer
What is the diameter of peroxisomes?
0.3-1.5 micrometer
What does the cilia consist of?
1- Basal Body. Kinetosome.
2- The shaft. Axoneme.
3- Rootlets.
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