Animal Histology Lab Report

OBJECTIVES
• To identify the structure of various types of animal tissues • To explain the organization of the tissues

HYPOTHESIS
• Various type of tissues can be identified their function by observing the shape and structure of the cells because different tissues have different functions.
• The usage of higher magnification of objective lens produces a better image.

INTRODUCTION
Internal structure of animal is made up cells. Cells aggregate and forms tissue. Animal tissues are classified into four types on the basis of their functions – epithelial tissue, connective tissue, muscle tissue and nervous tissue.

EPITHELIAL TISSUE
The covering and protective tissues in the animal body are epithelial tissues. It covers most organs and cavities within the body and forms a barrier to keep different body systems separate. Example: Skin, Lining of the mouth, lining of blood vessels, lung alveoli and kidney tubules

• Characteristics of epithelial tissue:

· Tightly packed and form a continuous sheet.
· Small amount of cementing material is present between them and almost no intercellular spaces.
· It plays an important role in regulating the exchange of materials between the body and the external environment and also between different parts of the body.
· Matrix is either absent or negligible
· Number of cells are large
Depending on the structures that correlate with their unique functions, epithelial tissues are classified into simple and stratified epithelium.

• Simple Epithelium: Cells are arranged in a single layer and does not contain matrix. There are four types of simple epithelium; squamous, columnar, cuboidal and glandular.
· Squamous: Thin and flat tissue and forms a delicate lining. They are arranged closely and jointed by cement material.
Example: Lining of blood vessels, heart and lymphatic tubes

· Columnar: Cells are broad and nucleus is oval in shape and is located in the centre or towards the narrow end Example: inner lining of alimentary canal, cystic duct

• Cuboidal: Cube shaped cells and provides mechanical support and helps in secretion and absorption. Example: Kidney tubules
· Glandular: Tissue folds inward and forms multicellular gland and secretes substances at the epithelial surface.  Stratified Epithelium: Cells are arranged in a many layers and are capable of cell division. Regions which are exposed to greater wear and tear such as epidermis of skin and lining of rectum are made up of stratified epithelium.

• CONNECTIVE TISSUE
Connective tissues are loosely packed tissues embedded in an intercellular matrix which may be jelly like, fluid, dense or rigid. The nature of matrix differs in concordance with the function of the particular connective tissue. It connects or binds the organs and acts as filling or packing between organs. Characteristics of connective tissue:
· Number of cells is less as compare to epithelial tissue
· Connect or binds the organs
· Act as filling material between the organs
· Intracellular substance is high
· Responsible for cell division of preexisting cells

• Types of connective tissue:
Areolar Connective Tissue: It is found between the skin and muscles, around blood vessels and nerves and in the bone marrow. It fills the space inside the organs, supports internal organs and helps in repair of tissues. It has dense matrix which consists of a network of fibers and an unorganized, homogeneous intercellular secretion. Fibers are white or yellow. White fibers are made up of collagen and non elastic, whereas yellow fibers are made up of elastin and are elastic in nature.

• Adipose tissue: Tissue present below the skin and between internal organs which contains fat globules. Fat inside the globules acts as an insulator.
• Compact Bone: Bone is a connective tissue and forms the
framework that supports the body. It is strong and nonflexible tissue and embedded in a hard matrix that is composed of
calcium and phosphorus compounds.
• Ligaments: Tissue present between two bones and is very elastic and has considerable strength. It contains very little matrix.

• Tendons: Tissue that connects muscles to bones and is fibrous with great strength but limited flexibility.
• Blood cells: Blood is another type of connective tissue which contains fluid matrix called plasma. Plasma contains red blood cells (RBCs), white blood cells (WBCs), and platelets. It also contains proteins, salts and hormones. Blood flows and transports gases, digested food, hormones and waste materials to different parts of the body.

• MUSCULAR TISSUE:
Tissue consists of elongated cells and responsible for movement in our body is called muscular tissue.  Elongated cells present in muscular tissue are called as muscle fiber. Muscle also contains special proteins called contractile proteins, which contract and relax to cause movement

• Type of Muscle fibers:
Striated muscle: It is also called as a voluntary muscle as it moves by conscious will. They are mostly attached to bones and help in body movement so also called as skeletal muscle. Under microscope it shows light and dark bands or striations when stained appropriately and hence called as striated muscle. The cells of this tissue are long, cylindrical, unbranched and multinucleate.

• Smooth muscle: Muscles that controls the movement of food in the alimentary canal or the contraction and relaxation of blood vessels are smooth muscle or involuntary muscle. The cells are long with pointed ends and Uninucleate. They are also called unstriated muscles. They are spindle-shaped.
• Cardiac muscle: Muscles of the heart show rhythmic contraction and relaxation throughout life and called cardiac muscles. They are cylindrical, branched and uninucleate. It is the occurrence of connecting structures called intercalary discs near terminal regions of muscle fibers. Intercalary disc

connects adjacent fibers.

• NERVOUS TISSUE:
Highly specialized tissue for transmitting stimulus very rapidly from one place to another within the body is called nervous tissue. Nerve impulse allows animals to move rapidly in response to stimuli. The brain, spinal cord and nerves are all examples of nervous tissue. The cells are called nerve cells or neurons

A neuron consists of a cell body with a nucleus and cytoplasm, from which long thin hair like parts arise. Usually each neuron has a single long part called the axon and many short branched parts called dendrites. An individual nerve cell may be up to a meter long. Many nerve fibers found together by connective tissue make up a nerve.  Nervous tissue establishes communication between different parts of the body, through conduction of nerve impulses.

APPARATUS AND MATERIALS
• Light microscope, epithelium tissue slides( squamous epithelium, cuboidal epithelium, columnar epithelium, ciliated columnar epithelium, stratified epithelium, pseudostratified epithelium), connective tissue (blood, bone, cartilage), muscle tissue (striated, smooth, cardiac) and nerve tissue (neuron).

PROCEDURE
• The slides given were examined under the microscope and the structure and organization of the tissues were observed.
• Each of the tissues given were drawn and labelled. Diagrams from the textbook was used assist in cell investigation.
A. Epithelium tissues
a) Squamous epithelium
b) Cuboidal epithelium
c) Columnar epithelium
d) Ciliated columnar epithelium
e) Pseudostratified ciliated columnar epithelium

Stratified squamous epithelium

g) Transitional epithelium

B. Connective tissue
a) Blood
i. Neutrophils
ii. Eosinophils
iii. Basophils
iv. Monocyte and lymphocyte
b) Bone
c) Cartilage
i. Hyaline cartilage
ii. Fibrocartilage
iii. Elastic cartilage

C. Muscle tissue
a) Striated
b) Smooth
c) Cardiac
D. Nerve tissue
d) Neuron

RESULTS
A. Epithelium tissues
a) Squamous epithelium

b) Cuboidal epithelium

c) Columnar epithelium

d) Ciliated columnar epithelium

e) Pseudostratified ciliated columnar epithelium

f) Stratified squamous epithelium

g) Transitional epithelium

B. Connective tissue
a) Blood
1) Neutrophils

2) Eosinophils

3) Basophils

4) Monocyte and lymphocyte

monocyte
lymphocyte

Bone

c) Cartilage
1) Hyaline cartilage

2) Fibrocartilage

3) Elastic cartilage

C. Muscle tissue
a) Striated

b) Smooth

a) Cardiac

D. Nerve tissue
a) Neuron

DISCUSSION
A. Epithelium tissues
a) Squamous epithelium
The nuclei appears to be flattened due to the shape of the cells. It is also scale-like It is observed that squamous epithelium are flattenedshaped. b) Cuboidal epithelium
The nuclei of these cells are large. The cells in the Cuboidal epithelium tissue appears to be square-shaped. As observed in the picture, the cells are arranged in a single layer. Therefore, the tissue is a simple cuboidal epithelial tissue.

c) Columnar epithelium
The nuclei of the cells are also elongatedThe cells in the picture are elongated, quite narrow and column-like. Hence, the name columnar epithelium.. The cells are arranged in a single layer. They usually have goblet cells that secretes mucous.

d) Ciliated columnar epithelium
The cells observed were from the trachea. It is a columnar
epithelium with a cilia on its free surface. The tissue has goblet cells that secrete mucus to moisten the air that passes through during respiration.
e) Pseudostratified ciliated columnar epithelium
The cells appear to be arranged in more than one layer.
However, they are arranged in only one layer. Hence, the tissue is a pseudostratified epithelial tissue. The cells are elongated indicating that they are columnar cells
f) Stratified squamous epithelium
The tissue observed has more than one layer. This indicates that the tissue is stratified. Besides that, the cells appear to be flatten-shaped indicating the type of cells are squamous cells.

g) Transitional epithelium
The cells observed are from the urinary bladder. The darker region are the transitional epithelium. These type of tissue consist of multiple layers of epithelial cells which can contract and expand. The transitional epithelium cells accommodate fluctuation of volume of the liquid in an organ such as the urinary bladder.

Connective tissue
a) Blood
i. Neutrophils
Neutrophil nucleus has a complex, lobulated shape.
ii. Eosinophils
The eosinophil generally has a nucleus with two lobes (bilobed), and cytoplasm filled many large granules.
iii. Basophils
Basophil has some platelets on the left. Nucleus in basophils are not notably lobulated.

Monocyte and lymphocyte
Lymphocyte’s nucleus is very large for the size of the cell and stains dark purple. Monocyte is the largest of the leukocytes and is agranular. The nucleus is most often “U” or kidney bean shaped; the cytoplasm is abundant and light blue.
b) Bone
Bone tissue are the main constituents of the skeletal tissue. The spots seen in the picture are the lacunae

c) Cartilage
i. Hyaline cartilage
Contains more collagen compared to hyaline.
ii. Fibrocartilage
Fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions.
iii. Elastic cartilage
Contains elastic bundles (elastin) scattered throughout the matrix. This provides a tissue which is stiff yet elastic.

C. Muscle tissue
a) Striated
It consists of light and dark bands. As shown in the diagram, a single skeletal muscle cell is long and approximately cylindrical in shape, with many nuclei located at the edges
(periphery) of the cell.
b) Smooth
Unlike Skeletal and Cardiac muscle tissue, Smooth muscle is not striated. Smooth muscle fibers are small and tapered – with the ends reducing in size, in contrast to the cylindrical shape of skeletal muscle. Each smooth muscle fiber has a single centrally located nucleus.

c) Cardiac
Cardiac muscle fibers are striated, branched (sometimes described as Y-shaped), and have a single central nucleus. These fibers are attached at their ends to adjoining fibers by thick plasma membranes called intercalated discs.

D. Nerve Tissue
• Neuron
From the observed slide, the structures that are in a darker shade is the neuron. The one at the centre is the cell body that has a nucleus right at the centre of it. The branches are the dendrites that extends from the cell body.

PRECAUTIONARY STEPS
1. The microscope lenses should be wiped with Kim wipe.
2. Use the microscope in a proper way while observing the tissue slides under it.

CONCLUSION
• Throughout the observation, the structure of squamous
epithelium consists of single layer of flat cells and the nucleus is located at the centre of cell. Here as, in the structure of cuboidal epithelium. It consists of a single layer of cube-like cell epithelium that attached to the basement membrane. It also contains goblet cells and has microvilli in some part of locations. The ciliated columnar epithelium is longitudinal shape and cilia are presence in the apical surface. The height of the cell is larger than its width. In the structure of stratified epithelium (oesophagus), it consists of several thick layer of cell and has columnar shape in the deep layer.

Besides that, squamous epithelium cells are formed on the apical layer. The pseudo stratified epithelium (trachea) consists of closely packed cells which appear to be arranged in several layers but mostly are attached to the basement membrane. The matrix of the blood is a liquid known as plasma. Blood consists of two types which are erythrocytes and leucocytes. In the structure of bone, tissue, it is characterized by a mineralized extracellular matrix. It consists of osteocyte which the osteocyte lays between lacunae and lamellae. The hyaline cartilage tissue is firm and elastic. It has cells which are known as chondrocytes.

Chondrocytes produce chondroitin and collagenous sulphate.
The chondrocytes is located in the discs and cups of some bone. In the structure of striated tissue, the skeletal muscle tissue contains numerous muscle fibres which is thin and has a very long fibre. Smooth muscle tissue consists of long sheets and has spindle-shape cells. Each of the cells containing a single nucleus. In the structure of cardiac muscle tissue, it is a cylindrical shape that appears to be striated and branched. Lastly, for the structure of nerve tissue, it divided into two main types of cell which is neuron and neuroglia. Each neuron consists of four parts, which is dendrite, cell body, axon and synaptic transmit.

REFERENCES

From internet:
1. Animal Biology- Animal Histology
http://
www.web-formulas.com/Biology_Topics/Animal-Biology-Animal
-Histology.aspx
2. Structure And Function Of Cartilage Tissues http://
www.ivyroses.com/HumanBody/Tissue/Tissue_Cartilage-Tissue.
php
3. Structure, Type and location of Cartilage https
://www.boundless.com/physiology/textbooks/boundless-anatomy-and -physiology-textbook/skeletal-tissue-6/cartilage-70/structure-t