DESCRIPTION OF CELLS AND TISSUES
An essential requirement in Histology is to be able to describe cells and
tissues unambiguously. The following list gives all the criteria which can
be used at light microscope level.
a) Relative size — e.g. compared to other cells in the tissue.
b) Shape — e.g. columnar, cuboidal, flattened, polyhedral.
c) Cytoplasmic reaction usually refers to acidophilia (usually
eosinophilia, i.e. affinity for eosin) or basophilia (usually
affinity for haematoxylin), although special stains may be used
for specific substances (e.g. fat or glycogen).
e) Cytoplasmic inclusions — e.g. granules, vacuoles.
e) Nuclear characteristics — e.g. shape, position within the cell,
size, staining pattern, presence or absence of nucleoli.
f) Surface specialisations — e.g. cilia.
g) Arrangement — cells are arranged to form tissues, e.g. in
single or multiple layers, cords or clumps; with variable
amounts of intercellular matrix which may be solid, fluid or
fibrous.
——————
HAEMATOXYLIN & EOSIN STAINING
Haematoxylin and eosin (usually abbreviated H&E) are two very
commonly used histological stains. It is most important to be clear
about their properties because the interpretation of cell function
depends upon a knowledge of the reaction (pH) of organelles.
Haematoxylin is a base and therefore tends to bind to acidic structures.
It stains blue. The most distinctive acid in cells is nuclear DNA,
consequently nuclei appear blue. Structures which are acidic are said to
be basophilic, i.e. they attract basic stains.
Eosin is acidic and therefore stains basic structures. It stains red. The
cytoplasm of most cells is slightly basic and therefore stains pink and is
said to be acidophilic.
Note that a knowledge of these properties allows you to interpret a
preparation made with an unknown stain. The nucleus is always acidic
and therefore defines the basic stain.
DESCRIPTION OF CELLS AND TISSUESAn essential requirement in Histology is to be able to describe cells andtissues unambiguously. The following list gives all the criteria which canbe used at light microscope level.a) Relative size — e.g. compared to other cells in the tissue.b) Shape — e.g. columnar, cuboidal, flattened, polyhedral.c) Cytoplasmic reaction usually refers to acidophilia (usuallyeosinophilia, i.e. affinity for eosin) or basophilia (usuallyaffinity for haematoxylin), although special stains may be usedfor specific substances (e.g. fat or glycogen).e) Cytoplasmic inclusions — e.g. granules, vacuoles.e) Nuclear characteristics — e.g. shape, position within the cell,size, staining pattern, presence or absence of nucleoli.f) Surface specialisations — e.g. cilia.g) Arrangement — cells are arranged to form tissues, e.g. insingle or multiple layers, cords or clumps; with variableamounts of intercellular matrix which may be solid, fluid orfibrous.——————HAEMATOXYLIN & EOSIN STAININGHaematoxylin and eosin (usually abbreviated H&E) are two verycommonly used histological stains. It is most important to be clearabout their properties because the interpretation of cell functiondepends upon a knowledge of the reaction (pH) of organelles.Haematoxylin is a base and therefore tends to bind to acidic structures.It stains blue. The most distinctive acid in cells is nuclear DNA,consequently nuclei appear blue. Structures which are acidic are said tobe basophilic, i.e. they attract basic stains.Eosin is acidic and therefore stains basic structures. It stains red. Thecytoplasm of most cells is slightly basic and therefore stains pink and issaid to be acidophilic.Note that a knowledge of these properties allows you to interpret apreparation made with an unknown stain. The nucleus is always acidicand therefore defines the basic stain.
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