Written By Priyanka Srivastava
Last Modified 21-06-2023

Animal Tissue: Structure, Characteristics & More

Animal Tissue: In mere simple words, all the animal cells are grouped together under animal tissue. Animal tissues vary in their structure, and origin along with their morphological characteristics too. The animal tissues are further divided into epithelial, connective, muscular and nervous tissues. Since tissues play a critical role in the overall performance of the body functions, students must know the entire information about animal tissues and what are the important distinguishing characteristics between the plant and animal tissues.

Animal tissues line up the body cavities of humans. Thus, all the students must know the types of animal tissues and their individual functions so that their idea of animal tissue culture with the types of animal tissue gets cleared. Read this article in order to know more about the importance of animal tissues.

Types of Animal Tissue: Functions and Origin

We have provided the types of Animal Tissue and their functions in a tabulated form below:

Tissue	Origin	Typical Function
Epithelial tissue	Ectoderm	Protection, secretion
Connective tissue	Mesoderm	Protection, attachment, support, storage, strength, transport
Muscular tissue	Mesoderm	Movement, locomotion
Nervous tissue	Ectoderm	Control and coordination

Animal Tissue Culture- Diagram

Check the diagram to have an understanding of Animal Tissue better to score good marks:

What are the 4 Types of Animal Tissues?

There are four types of Animal Tissues and each of them have been explained in a detailed manner below:

Epithelial Tissue
Muscle Tissue
Connective Tissue
Neural Tissue

Epithelial Tissue

An epithelium (Greek Epi – upon; thele – nipple) is a sheet of cells that covers an internal or external surface.
Epithelial tissue is made of compactly arranged cells with no intercellular matrix and forms a continuous sheet. Junctional complexes like desmosomes, gap junctions help in holding the cells together.
It has power or regeneration throughout life. It is non-vascular in nature. Epithelial cells lie on the basement membrane, which is non-cellular and contains matrix protein, collagen.

Location: It covers the outer surface of the body and internal organs. It lines the body cavities. Like it lines the outer surface skin, inner lining of the mouth, alimentary canal, nose, lungs, etc.

Function: These are protective in nature.
It is of the following types: –

Type of Epithelium	Characteristic Feature	Location in Body
Squamous Epithelium	1. Cells are flattened, thin. 2. They are also called the pavemented or tessellated epithelium. 3. Cells are tile-like, polygonal and compactly arranged.	1. Blood vessels, heart, lymph vessels. 2. Skin, inner lining of mouth. 3. Abdominopelvic cavities (Mesothelium). 4. They are protective in nature.
Cuboidal Epithelium	1. Cells are short, cube-like with a round nucleus.	1. Small ducts of glands like pancreas, kidneys, salivary glands. 2. They may be secretory in nature. Absorption and excretion are also functions of these tissues.
Columnar Epithelium	1. Cells are pillar-like or column-like. 2. Nucleus is towards the base.	1. Lining of the alimentary canal. 2. Stomach and small intestine. 3. Goblet cells secrete mucus. 4. They are mainly secretory.
Ciliated Columnar Epithelium	1. The cells have cilia on their apices.	1. They help in movement of material by ciliary movement. 2. Present in oviduct, respiratory passages.
Glandular Columnar Epithelium	1. These cells are long, pillar-like and store for secretion.	1. All types of exocrine glands.
Stratified Epithelium	1. The cells are present in layers. 2. The upper layer cells do not divide.	1. Keratinised stratified epithelia are found in nails, hairs, etc. 2. Non-keratinised stratified epithelia are found in conjunctiva of eyes, vagina, etc.

Muscular Tissue

Muscular tissue forms the muscles in our body which can contract and relax. These are made of muscle cells. Muscle cells are long and elongated so-called muscle fibres and contain actin and myosin contractile proteins.

Function: Contractile proteins present in them helps in contraction and relaxation which brings movement and locomotion.
Following three types of muscular tissues are present: –

Striated Muscle	Non-striated Muscle	Cardiac Muscle
They are present in limbs, body wall, tongue, pharynx, beginning of oesophagus.	They are present in oesophagus, urinary bladder, urinogenital tract, vessels, iris of eyes, the dermis of skin.	They are present in the myocardial layer of heart.
Cylindrical shape.	Spindle-shaped with tapering ends.	Cylindrical shape.
Not branched.	Not branched.	Branched.
Cells are multinucleated or syncytial.	Uninucleated cells.	Uninucleated cells.
Voluntary movement.	Involuntary movement.	Involuntary movement.
Bound by sarcolemma	Sarcolemma absent	Sarcolemma present.
Very fast contraction.	Slow contraction.	Autorhythmic contraction.
Gets fatigue easily.	Does not get fatigue easily.	Never gets fatigue.
Light (Isotropic) and dark (Anisotropic) bands present.	Bands altogether absent.	Thin, feeble bands are present.
Intercalated discs are absent.	Intercalated discs are absent.	Oblique bridges or intercalated discs are present.
Nerve supply is from CNS.	Nerve supply is from ANS.	Never supply is from the brain and ANS.
Abundant blood supply is present for the cells.	Blood supply is scanty.	Blood supply is abundant
Muscle cells have less mitochondria.	Muscle cells have more mitochondria.	Huge number of mitochondria are present in each cell.

Connective Tissue

Connective tissue connects one tissue with the other tissue and organs. This helps them to keep various organs in their position.

It is of the following three types:
a. Skeletal or Supportive Connective Tissue-
i. Bone
ii. Cartilage
b. Loose Connective Tissue
i. Areolar
ii. Adipose
c. Dense Connective Tissue
i. Tendon
ii. Ligament
d. Fluid connective tissue
i. Blood
ii. Lymph

Skeletal or Supportive Connective Tissue

It comprises cartilage and bones.

1. Cartilage– This connective tissue is present in the ends of the bones. It also lies in the nose tips, ear pinna, etc. It is a non-porous tissue, has no blood vessels, and has an intercellular substance called matrix. Matrix is soft in cartilage. It is a semi-transparent substance. It is softer than bone and has elasticity. Mature cartilage cells, found in lacunae are larger, with fewer filopodia, and are called Chondrocytes.

Function: It provides support and flexibility at the joints and acts as a shock absorber.

2. Bone– It is the main supportive organ of the body. Its matrix is hard made of calcium and phosphorus salts. It is a porous tissue. It has a rich supply of blood and neurons. Bone cells are called Osteocytes.

Function: It forms the endoskeleton of bony fishes to mammals. It gives shape and support to the body. It is attached to muscles that help in locomotion. It protects organs and acts as a storehouse of calcium and phosphorus.

Loose Connective Tissue

It comprises areolar tissue, adipose tissue, tendons and ligaments.

1. Areolar tissue: This tissue binds our skin to the underlying tissues. They form the mass of our body. This is also called loose connective tissue. This is one of the most common and abundant loose connective tissues. They contain fibroblasts and mast cells.
2. Adipose tissue: It contains cells with fat globules. The cells are called adipocytes. This is also called loose connective tissue. There are two types, white fat and brown fat.

Dense Connective Tissue

This is mainly made up of closely packed bundles of collagen fibres with very little matrix.

1. Tendons: It attaches muscle to a bone. It is formed of white fibrous connective tissue. It is tough and flexible. This is a class of dense connective tissue. They are composed of white fibrous (collagen) bands or bundles. Fibroblasts are arranged between these bundles.
2. Ligament: It attaches bone to a bone. It is formed of yellow fibrous connective tissue. It is elastic and flexible. This is a class of dense connective tissue. They are composed of yellow fibres in bundles or networks. The fibres are much thicker as compared to white fibres.

Fluid Connective Tissue

It comprises blood and lymph. Because of its fluid nature, it is concerned with the transportation of nutrients.

1. Blood: It is a fluid connective tissue. It comprises different types of cells which are scattered in the plasma. Blood comprises blood cells and plasma. Blood cells are like WBCs, RBCs, and platelets. Mature erythrocytes and platelets are enucleated (without nucleus). Whereas the shapes of nuclei in WBCs are varied. There are two types of WBCs, namely, granulocytes and agranulocytes. Monocytes and lymphocytes are agranulocytes, which help in body defence. Eosinophils, basophils, and neutrophils are granulocytes.

Function:
i. Haemoglobin in RBCs (erythrocytes) helps in the transportation of oxygen and nutrients.
ii. WBCs or leukocytes help in fighting with germs and the infection caused.
iii. Platelets or thrombocytes help in clotting of blood.

2. Lymph: It consists of WBCs and blood plasma. As it is devoid of RBCs and platelets, it is of pale colour and does not coagulate. It is formed because of the oozing of blood from capillaries and forms a separate channel called lymph vessels.

Function: Its main function is to fight infections. Lymph is also an important carrier for nutrients, hormones, etc. In the intestinal villi, fats are absorbed through the lymph.

Neural Tissue

Nervous tissue is mainly composed of neurons and glial cells constitute the nervous system.

1. Neurons: The functional unit of the nervous tissue is neurons or nerve cells. Each neuron has a cyton, axon, axon terminals. Cyton or the cell body has dendrites. The cell body has a nucleus in it and many Nissl’s granules. Neurons can be myelinated and unmyelinated. If myelin sheath is present in the axon, it helps in fast conduction of nerve impulses in comparison to unmyelinated neurons. Neurons do not divide.

Function: It helps in the conduction of nerve impulses to various parts of the body.

2. Neuroglia or glial cells are the non-nervous cells present along with, over and between neurons in CNS, ganglia, and retina. They are of two types, microglia and macroglia.

Animal Cell Culture: Summary

Animal tissue refers to the group of cells of similar structure and function in plant and animal tissues. It is of the following types: Epithelial tissue, Muscle tissue, Connective tissue, Neural tissue. Epithelial tissue covers the outer surface of the body and internal organs. It lines the body cavities. It is protective in function. Muscular tissue forms the muscles in our body which can contract and relax.

It helps in voluntary and involuntary movement. Connective tissue connects one tissue with the other tissue and organs. This helps them to keep various organs in their position. Nervous tissue constitutes the nervous system. It is made of neurons. Its function is contraction and relaxation.

Frequently Asked Questions on Animal Tissue

Q.1: Why are animal tissues important?
Ans: a. Protection
b. Secretion
c. Absorption
d. Voluntary and involuntary movement
e. Nerve impulse conduction
f. Transport of oxygen and nutrients.

Q.2: Name one internal organ where smooth muscles are present.
Ans: The myometrium layer of the uterus contains smooth muscle. Oesophagus also has smooth muscles.

Q.3: What is animal tissue and its types?
Ans: Animal tissue refers to the group of cells having similar structures and performing a particular function in animals is called animal tissue. Epithelial tissue, Muscular tissue, Connective tissue, Nervous tissue are its types.

Q.4: What are the \(4\) types of tissues in animals?
Ans: a. Epithelial tissue
b. Muscular tissue
c. Connective tissue
d. Nervous tissue

Q.5: Where is the nervous tissue not found?
Ans: In tendons, nervous tissue is not found.

Q.6: Why is blood called connective tissue?
Ans: Connective tissue is to connect and anchor various tissues and body organs. Blood performs the same function so comes under connective tissue.