Histology
Lecture 1, 28 October 2024
Epithelia and gland tissue
What is studied in cell biology and histology?
Cell biology: molecule and cell component
Histology: cell, tissue and organ
Microscope:
-light microscope: 0.2 micrometer resolution
-electron microscope: transmission EM: 0.2 nanometer
Slide preparation:
1) Fixation
2) Imbedding
3) Cutting
4) Cytological staining
4 basic type of tissue:
There are 200 di erent cell types, organised in 4 basic type of tissues:
Nervous tissue Muscle tissue
Connective tissue Epithelial tissue
(ex: blood is a connective
tissue)
Basic tissue type are functionally organised in organs.
Cell type that are pert of the same basic tissue type can look much di erent. They share the same
embryonic origin.
ff ff
, Germ layers (group of cells in an embryo that form during early
development and gives raise to all tissues and organ) are 3:
-ectoderm: from structure like skin and nervous tissue
-mesoderm: digestive tissue, lung
-endoderm: muscle, connective tissue (from mesenchyme: mesoderm
rst forms mesenchyme, which then di erentiates to create muscle and
connective tissues in the body)
Epithelial tissue
Tissues existing of cell that are tightly connected to each other. Derives from one of the primary
cell layers.
Two type:
-covering epithelia (skin)
-glans (invagination of epithelial layers)
Classi ed based on embryonic origin (ecto-, endo-, or mesodermal), morphology (shape of the
cells) and cell organisation (number of cell layers: strata)
Shape of the cell:
-squamous
-cuboidal
-columnar
-transitional (change between
squamous and cuboidal)
Cell layers:
-simple
-strati ed or pseudo strati ed
Characteristic of epithelia:
-no blood circulation
-surface specialisation
-presence of basal membrane
-polarized: their structure and function di er from the top (apical) and the bottom (baso-lateral).
Apical:
-microvilli: increase surface area. Core of microvillus made of actin laments, which are a type of
cytoskeletal element (provide structural support)
-cilia: movement substance along cell surface and sensory function. Are 5x larger then microvilli.
In cilia there are microtubule, they can change in length, cause of the tubular that can contract
Baso-lateral: connect the underlying tissues
Intercellular connection:
Tight junction (zonula occludens):
-round the whole cell
-TJ proteins function like a zipper
Function:
-prevent transport between cells
-membrane protein are compartmentalised (apical and
basolateral) to keep them separated
Adhesion belt (zonula adhaerens):
-round the whole cell
-adhesion between cells
-made by transmembrane-linker proteins: cadherins
-intercellular: small, widened space
-intracellular: connected with actin
fi fi fi ff ff fi
, Gap junctions (nexus):
-intercellular transport: 1.5 nm
-transmembrane protein: connexins
-transport of ions, amino acids, molecules <1kDa, certain hormones
Desmosomes:
-not round the whole cell
-makes the strongest connection between cells
-intracellular: connected with intermediate laments
(keratin, vimentin, desmin, etc.)
Hemidesmosomes:
Integrins (transmembrane-linker proteins): connect the cell (its
intermediate laments) with connective tissues underneath.
Basal domain:
-hemidesmosomes
-basal lamina
-plasma membrane invagination (basal labyrinth),
surface area increase, mitochondria
fi fi
, In summary:
Lecture 1, 28 October 2024
Epithelia and gland tissue
What is studied in cell biology and histology?
Cell biology: molecule and cell component
Histology: cell, tissue and organ
Microscope:
-light microscope: 0.2 micrometer resolution
-electron microscope: transmission EM: 0.2 nanometer
Slide preparation:
1) Fixation
2) Imbedding
3) Cutting
4) Cytological staining
4 basic type of tissue:
There are 200 di erent cell types, organised in 4 basic type of tissues:
Nervous tissue Muscle tissue
Connective tissue Epithelial tissue
(ex: blood is a connective
tissue)
Basic tissue type are functionally organised in organs.
Cell type that are pert of the same basic tissue type can look much di erent. They share the same
embryonic origin.
ff ff
, Germ layers (group of cells in an embryo that form during early
development and gives raise to all tissues and organ) are 3:
-ectoderm: from structure like skin and nervous tissue
-mesoderm: digestive tissue, lung
-endoderm: muscle, connective tissue (from mesenchyme: mesoderm
rst forms mesenchyme, which then di erentiates to create muscle and
connective tissues in the body)
Epithelial tissue
Tissues existing of cell that are tightly connected to each other. Derives from one of the primary
cell layers.
Two type:
-covering epithelia (skin)
-glans (invagination of epithelial layers)
Classi ed based on embryonic origin (ecto-, endo-, or mesodermal), morphology (shape of the
cells) and cell organisation (number of cell layers: strata)
Shape of the cell:
-squamous
-cuboidal
-columnar
-transitional (change between
squamous and cuboidal)
Cell layers:
-simple
-strati ed or pseudo strati ed
Characteristic of epithelia:
-no blood circulation
-surface specialisation
-presence of basal membrane
-polarized: their structure and function di er from the top (apical) and the bottom (baso-lateral).
Apical:
-microvilli: increase surface area. Core of microvillus made of actin laments, which are a type of
cytoskeletal element (provide structural support)
-cilia: movement substance along cell surface and sensory function. Are 5x larger then microvilli.
In cilia there are microtubule, they can change in length, cause of the tubular that can contract
Baso-lateral: connect the underlying tissues
Intercellular connection:
Tight junction (zonula occludens):
-round the whole cell
-TJ proteins function like a zipper
Function:
-prevent transport between cells
-membrane protein are compartmentalised (apical and
basolateral) to keep them separated
Adhesion belt (zonula adhaerens):
-round the whole cell
-adhesion between cells
-made by transmembrane-linker proteins: cadherins
-intercellular: small, widened space
-intracellular: connected with actin
fi fi fi ff ff fi
, Gap junctions (nexus):
-intercellular transport: 1.5 nm
-transmembrane protein: connexins
-transport of ions, amino acids, molecules <1kDa, certain hormones
Desmosomes:
-not round the whole cell
-makes the strongest connection between cells
-intracellular: connected with intermediate laments
(keratin, vimentin, desmin, etc.)
Hemidesmosomes:
Integrins (transmembrane-linker proteins): connect the cell (its
intermediate laments) with connective tissues underneath.
Basal domain:
-hemidesmosomes
-basal lamina
-plasma membrane invagination (basal labyrinth),
surface area increase, mitochondria
fi fi
, In summary:
