BIOD151 (A&P I) Lab #7- Histology of Epithelial Tissue
Histology- This is the study of tissue and how they are arranged. This is also referred
to as a Microscopic Anatomy.
Understanding the microscopic anatomy helps us to understand how the physiology of
the body works.
Gross Anatomy- This is where we generally look at things from a gross standpoint,
meaning we can see structures with the naked eye and we can touch them.
What makes up a tissue?
Recall the hierarchy of the body:
1. Cells- smallest unit of life
2. Tissues- cells grouped together to form a tissue to perform a function
3. Organ- tissues grouped together to form an organ.
Tissues are made up of similar cells that group together to form a tissue that will
perform a specific function.
Recall that cells are the smallest unit of life that carry out a particular function. For
example, a muscle cell is specialized to perform muscle contraction, and other cells are
responsible for performing protein synthesis.
Organ- These are tissues grouped together. This is a structure with definite boundaries
that will perform a job depending on the types of cells and the arrangement of the
tissues found in the organ.
How do these organs derive their function?
To determine this we have to look at the cell type and the arrangement of the tissues.
We first have to look at the four primary types of tissues found in the body:
Types of Tissues in the body
1. Epithelial Tissue- Functions in secretions of waste, absorption and protection
2. Connective Tissue- Helps to bind tissues together and helps to anchor certain
organs to body cavities. It performs a connective/supportive role
3. Nervous Tissue- A very special tissue that serves the role of communication in
the body. Nerve signals are like the electric wiring in the body.
4. Muscular Tissue- Specialized for muscle contraction and general movement
,What differentiates these types of tissues? What makes them different?
Looking at tissue composition, we have discussed that tissues are made of similar types
of cells that join together to perform a specific function.
In addition to cells, the tissues contain something called matrix.
Matrix is defined as an extracellular material. This matrix is made up of two things:
1. Ground substance- this is also referred to as interstitial fluid or extracellular
fluid. It is made up of water, nutrients, minerals, gases and different compositions
depending on the type of tissue where this matrix can be found
2. Protein Fibers
In summary, a tissue is made up of cells and matrix.
The primary types of tissues in the body is differentiated by the different types
of cells found, the characteristics of the matrix seen in the tissue and the ratio
between the cellular content and the matrix. For example, some tissue types may
have a large amount of cells and a small amount of matrix. Some tissue types
may have the opposite, which is a smaller cellular content with a large amount
of matrix.
How did the tissues develop in the body? Where do the tissues come from?
At fertilization, there is a fertilized egg, which is the start of human development.
This small cell will divide into smaller cells which will then group themselves into similar
functional groups and form Three Primary Germ Layers:
1. Ectoderm- this is the first and outermost germ layer. The ectoderm is an
arrangement of tissue that will finally differentiate and give rise to the
Epidermis, which is the skin, and also the nervous tissue. In summary,
the ectoderm gives rise to some of our epithelial tissue and some of our
nervous tissue.
2. Mesoderm- this is the middle germ layer. The mesoderm starts out as a very
loosely organized group of cells and it will further differentiate into a layer called
the Mesenchyme. The mesenchyme is a gelatinous tissue that is composed of
protein fibers and branching-like cells called fibroblasts. The fibroblasts are
immature cells that are unspecialized or undifferentiated but they will grow and
differentiate and specialize into specific cells that will eventually give rise to more
, of our tissue types such as our connective tissue proper. Mesenchyme not
only gives rise to our connective tissue proper but it will also give rise to cartilage,
bone, muscle and blood.
3. Endoderm- This gives rise to the mucous membranes in our digestive and
respiratory tracts, and it will also give rise to some digestive glands. These
mucous membranes will encompass some epithelial tissue.
In summary, the primary class of tissue called epithelial tissue is coming from
the ectoderm and the endoderm in the primary germ layers.
Epithelial Tissue
General characteristics of the epithelial tissue include:
1. The location of the epithelial tissue is generally covering body surfaces
and covering or forming a lining around several body organs and body
cavities.
2. The structure- Remember that all tissues are made up of cells and matrix. So
how is epithelial tissue structured? Meaning how is it formed and what is the
ratio of these substances together?
a. Epithelial tissue contains a large amount of cell content so it
contains closely packed cells with very little matrix in between those
cells.
b. It appears as a flat continuous sheet of cells, and it can be either one
layer of cells or several layers.
c. Epithelial tissue is penetrated by nerves, meaning that it has a direct
nerve supply. If it has a nerve supply, this means that we can feel
something. For example, if something is cutting our skin, we can detect
that sensation, so the nerves will send that message to the brain.
d. Epithelial tissue is considered to be an avascular tissue, which
means that it does not have a direct blood supply.
e. Every layer of epithelial tissue has a separate layer underneath it called a
Basement Membrane. Epithelial tissue is adhered to a basement
Histology- This is the study of tissue and how they are arranged. This is also referred
to as a Microscopic Anatomy.
Understanding the microscopic anatomy helps us to understand how the physiology of
the body works.
Gross Anatomy- This is where we generally look at things from a gross standpoint,
meaning we can see structures with the naked eye and we can touch them.
What makes up a tissue?
Recall the hierarchy of the body:
1. Cells- smallest unit of life
2. Tissues- cells grouped together to form a tissue to perform a function
3. Organ- tissues grouped together to form an organ.
Tissues are made up of similar cells that group together to form a tissue that will
perform a specific function.
Recall that cells are the smallest unit of life that carry out a particular function. For
example, a muscle cell is specialized to perform muscle contraction, and other cells are
responsible for performing protein synthesis.
Organ- These are tissues grouped together. This is a structure with definite boundaries
that will perform a job depending on the types of cells and the arrangement of the
tissues found in the organ.
How do these organs derive their function?
To determine this we have to look at the cell type and the arrangement of the tissues.
We first have to look at the four primary types of tissues found in the body:
Types of Tissues in the body
1. Epithelial Tissue- Functions in secretions of waste, absorption and protection
2. Connective Tissue- Helps to bind tissues together and helps to anchor certain
organs to body cavities. It performs a connective/supportive role
3. Nervous Tissue- A very special tissue that serves the role of communication in
the body. Nerve signals are like the electric wiring in the body.
4. Muscular Tissue- Specialized for muscle contraction and general movement
,What differentiates these types of tissues? What makes them different?
Looking at tissue composition, we have discussed that tissues are made of similar types
of cells that join together to perform a specific function.
In addition to cells, the tissues contain something called matrix.
Matrix is defined as an extracellular material. This matrix is made up of two things:
1. Ground substance- this is also referred to as interstitial fluid or extracellular
fluid. It is made up of water, nutrients, minerals, gases and different compositions
depending on the type of tissue where this matrix can be found
2. Protein Fibers
In summary, a tissue is made up of cells and matrix.
The primary types of tissues in the body is differentiated by the different types
of cells found, the characteristics of the matrix seen in the tissue and the ratio
between the cellular content and the matrix. For example, some tissue types may
have a large amount of cells and a small amount of matrix. Some tissue types
may have the opposite, which is a smaller cellular content with a large amount
of matrix.
How did the tissues develop in the body? Where do the tissues come from?
At fertilization, there is a fertilized egg, which is the start of human development.
This small cell will divide into smaller cells which will then group themselves into similar
functional groups and form Three Primary Germ Layers:
1. Ectoderm- this is the first and outermost germ layer. The ectoderm is an
arrangement of tissue that will finally differentiate and give rise to the
Epidermis, which is the skin, and also the nervous tissue. In summary,
the ectoderm gives rise to some of our epithelial tissue and some of our
nervous tissue.
2. Mesoderm- this is the middle germ layer. The mesoderm starts out as a very
loosely organized group of cells and it will further differentiate into a layer called
the Mesenchyme. The mesenchyme is a gelatinous tissue that is composed of
protein fibers and branching-like cells called fibroblasts. The fibroblasts are
immature cells that are unspecialized or undifferentiated but they will grow and
differentiate and specialize into specific cells that will eventually give rise to more
, of our tissue types such as our connective tissue proper. Mesenchyme not
only gives rise to our connective tissue proper but it will also give rise to cartilage,
bone, muscle and blood.
3. Endoderm- This gives rise to the mucous membranes in our digestive and
respiratory tracts, and it will also give rise to some digestive glands. These
mucous membranes will encompass some epithelial tissue.
In summary, the primary class of tissue called epithelial tissue is coming from
the ectoderm and the endoderm in the primary germ layers.
Epithelial Tissue
General characteristics of the epithelial tissue include:
1. The location of the epithelial tissue is generally covering body surfaces
and covering or forming a lining around several body organs and body
cavities.
2. The structure- Remember that all tissues are made up of cells and matrix. So
how is epithelial tissue structured? Meaning how is it formed and what is the
ratio of these substances together?
a. Epithelial tissue contains a large amount of cell content so it
contains closely packed cells with very little matrix in between those
cells.
b. It appears as a flat continuous sheet of cells, and it can be either one
layer of cells or several layers.
c. Epithelial tissue is penetrated by nerves, meaning that it has a direct
nerve supply. If it has a nerve supply, this means that we can feel
something. For example, if something is cutting our skin, we can detect
that sensation, so the nerves will send that message to the brain.
d. Epithelial tissue is considered to be an avascular tissue, which
means that it does not have a direct blood supply.
e. Every layer of epithelial tissue has a separate layer underneath it called a
Basement Membrane. Epithelial tissue is adhered to a basement
