Histology of Epithelial Tissue
Histology: the study of tissues and how they are arranged (microscopic anatomy). The
understanding of microscopic anatomy is crucial to understanding the physiology how our body
works.
Gross anatomy - seen with naked eye, can touch
Microscopic anatomy - for understanding physiology
- Tissue - made up of similar cells that group together to form a tissue that will perform a
speci c function.
- Cell - the smallest unit of life, that carry out a particular function. These cells perform a
specialized function like muscle contraction or protein synthesis. They generally group together
to form a tissue, and tissue join together to form an organ
- Organ: structure with de nite boundaries that will perform a job depending on the types of
cells and the arrangement of the tissue found in the organ.
- How do the organs derive their functions? Cell type and arrangement of the tissue.
Four primary classes of tissue found in body:
- Epithelial Tissue - works in secretion and absorption. Also protection and secretion of waste.
- Connective Tissue - help bind tissues together; anchor certain organs to body cavities.
Connective/supportive role.
- Nervous Tissue - very specialized. Like wiring. Communication in the body.
- Muscular Tissue - muscle contraction and general movement.
Tissues are made up of cells and matrix.
Matrix - extracellular material. Made up of: 1) Ground substance (interstitial uid or
extracellular uid). Made up of water, nutrients, minerals, gases in different compositions
depending on type of tissue where matrix is found. 2) Contains protein bers.
How are these tissues different from each other?
The primary classes of tissues are different because of different types of cells, characteristics of
the matrix we see in the tissue, and the ratio between the cellular content and the matrix.
How do tissues develop in the body
- At fertilization human development starts with one fertilized egg. This cell will divide and
divide into smaller cells which will then group themselves into similar functional groups called
three primary germ layers:
- Ectoderm - outer germ layer. arrangement of tissue that differentiate and gives rise to our skin
(epithelial tissue) and nervous tissue.
- Mesoderm (middle layer) - starts as loosely organized group of cells, then differentiate into
mesenchyme layer — mesenchyme is gelatinous tissue composed of proteins bers and
branching-like cells called broblasts. Fibroblasts are immature cells that are unspecialized or
undifferentiated but will grow and differentiate/specialize into speci c cells that will eventually
give rise to more of tissue types like connective tissue proper. Mesenchyme also gives rise to
cartilage, bone, muscle, and blood
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, - Endoderm - most inner layer of our germ layers. Will give rise to the mucous membranes in
digestive and respiratory tracts, and also to some digestive glands.
These mucous membranes will encompass some epithelial tissue.
• Note* epithelial tissue is coming from ectoderm and endoderm.
Epithelial tissue
- Location — generally covers body surfaces or lines around body organs. Also lines body
cavities and several organs in the body.
- Structure of epithelial tissue
- contains large cellular content; contains closely packed cells with little matrix in between
- Appears as a at and continuous sheet of cells and it can be one or several layers of cells.
- Penetrated by direct nerve supply. We can feel if something cuts skin, for example.
- No direct blood supply; avascular tissue.
- Every layer of epithelial tissue is adhered to a basement membrane. Which will connect it to
the underlining tissue beneath it; most commonly a connective tissue type. The connective
tissue is where the epithelial draws its blood supply from.
- One surface of epithelial tissue is adhered to basement membrane and the other is a free
(apical) surface.
- Cells are constantly dividing. If we lose cells we have a supply of cells waiting to replace them.
Example: skin sloughs off every day.
How is epithelial tissue classi ed? By cell type and shape and arrangement of these cells.
Squamous epithelium - at and scaly cel
Cuboidal epithelium - appear round or square
Columnar epithelium - tall and narrow cells (taller than they are wide)
Cell arrangement:
Simple arrangement - one layer of cells and all will touch the basement membrane. Basal surface
is part of cell that’s in contact with basement membrane; apical or free surface is the other side.
Strati ed arrangement - two or more layers of cells.
Pseudostrati ed epithelium - mostly seen with columnar cells. This is when the cell arrangement
looks strati ed, but when you look closely, every cell is touching the base membrane but not all
are touching the free surface. Like tree; all anchored, but different heights.
I. SIMPLE arrangmen
This study source was downloaded by 100000897367967 from CourseHero.com on 06-24-2025 06:19:21 GMT -05:00
https://www.coursehero.com/file/250325343/Lab-7pdf/
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Histology: the study of tissues and how they are arranged (microscopic anatomy). The
understanding of microscopic anatomy is crucial to understanding the physiology how our body
works.
Gross anatomy - seen with naked eye, can touch
Microscopic anatomy - for understanding physiology
- Tissue - made up of similar cells that group together to form a tissue that will perform a
speci c function.
- Cell - the smallest unit of life, that carry out a particular function. These cells perform a
specialized function like muscle contraction or protein synthesis. They generally group together
to form a tissue, and tissue join together to form an organ
- Organ: structure with de nite boundaries that will perform a job depending on the types of
cells and the arrangement of the tissue found in the organ.
- How do the organs derive their functions? Cell type and arrangement of the tissue.
Four primary classes of tissue found in body:
- Epithelial Tissue - works in secretion and absorption. Also protection and secretion of waste.
- Connective Tissue - help bind tissues together; anchor certain organs to body cavities.
Connective/supportive role.
- Nervous Tissue - very specialized. Like wiring. Communication in the body.
- Muscular Tissue - muscle contraction and general movement.
Tissues are made up of cells and matrix.
Matrix - extracellular material. Made up of: 1) Ground substance (interstitial uid or
extracellular uid). Made up of water, nutrients, minerals, gases in different compositions
depending on type of tissue where matrix is found. 2) Contains protein bers.
How are these tissues different from each other?
The primary classes of tissues are different because of different types of cells, characteristics of
the matrix we see in the tissue, and the ratio between the cellular content and the matrix.
How do tissues develop in the body
- At fertilization human development starts with one fertilized egg. This cell will divide and
divide into smaller cells which will then group themselves into similar functional groups called
three primary germ layers:
- Ectoderm - outer germ layer. arrangement of tissue that differentiate and gives rise to our skin
(epithelial tissue) and nervous tissue.
- Mesoderm (middle layer) - starts as loosely organized group of cells, then differentiate into
mesenchyme layer — mesenchyme is gelatinous tissue composed of proteins bers and
branching-like cells called broblasts. Fibroblasts are immature cells that are unspecialized or
undifferentiated but will grow and differentiate/specialize into speci c cells that will eventually
give rise to more of tissue types like connective tissue proper. Mesenchyme also gives rise to
cartilage, bone, muscle, and blood
This study source was downloaded by 100000897367967 from CourseHero.com on 06-24-2025 06:19:21 GMT -05:00
fihttps://www.coursehero.com/file/250325343/Lab-7pdf/
fl fi
fi
.
?
fi fi flfi
, - Endoderm - most inner layer of our germ layers. Will give rise to the mucous membranes in
digestive and respiratory tracts, and also to some digestive glands.
These mucous membranes will encompass some epithelial tissue.
• Note* epithelial tissue is coming from ectoderm and endoderm.
Epithelial tissue
- Location — generally covers body surfaces or lines around body organs. Also lines body
cavities and several organs in the body.
- Structure of epithelial tissue
- contains large cellular content; contains closely packed cells with little matrix in between
- Appears as a at and continuous sheet of cells and it can be one or several layers of cells.
- Penetrated by direct nerve supply. We can feel if something cuts skin, for example.
- No direct blood supply; avascular tissue.
- Every layer of epithelial tissue is adhered to a basement membrane. Which will connect it to
the underlining tissue beneath it; most commonly a connective tissue type. The connective
tissue is where the epithelial draws its blood supply from.
- One surface of epithelial tissue is adhered to basement membrane and the other is a free
(apical) surface.
- Cells are constantly dividing. If we lose cells we have a supply of cells waiting to replace them.
Example: skin sloughs off every day.
How is epithelial tissue classi ed? By cell type and shape and arrangement of these cells.
Squamous epithelium - at and scaly cel
Cuboidal epithelium - appear round or square
Columnar epithelium - tall and narrow cells (taller than they are wide)
Cell arrangement:
Simple arrangement - one layer of cells and all will touch the basement membrane. Basal surface
is part of cell that’s in contact with basement membrane; apical or free surface is the other side.
Strati ed arrangement - two or more layers of cells.
Pseudostrati ed epithelium - mostly seen with columnar cells. This is when the cell arrangement
looks strati ed, but when you look closely, every cell is touching the base membrane but not all
are touching the free surface. Like tree; all anchored, but different heights.
I. SIMPLE arrangmen
This study source was downloaded by 100000897367967 from CourseHero.com on 06-24-2025 06:19:21 GMT -05:00
https://www.coursehero.com/file/250325343/Lab-7pdf/
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flt
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