Tissues

Plant tissue and animal tissue

%%Meristematic Tissues :%%

The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants.

1. They lack vacuoles
2. They are very active
3. They have a thin cell wall made up of cellulose
4. They have Dense cytoplasm

@@Apical Meristems@@ - The Apical Meristematic tissue is a tissue found in the plant which is responsible for plant growth and found in the root tips as well as the tips of new shoots and leaves. One of three types of meristems, or tissue that can divide into various cell types, is the Apical Meristem. In plants, the meristem is the tissue where development takes place. Apical growth refers to growth that occurs at the plant's top and bottom tips. Apical Meristems give rise to the primary plant body and are in charge of root and shoot extension. \n @@Lateral Meristems@@ - Some plants, like some people, do not just grow up, but they grow out, as well. This, however, is a much different process in plants and humans. Plants that grow out, like trees and other woody plants, also contain a lateral meristem, from the Latin latus, meaning 'side.' A lateral meristem causes a plant to grow laterally. \n Intercalary Meristems - The meristematic tissues that are present at the base of internodes of stem and petioles of leaves are known as Intercalary meristem. The function of these tissues is to promote the growth of the plants by elongating the nodes and internodes present at the leaves and stems.

Permanent Tissue

Permanent tissues are made of meristematic cells, that has definite form and shape and have lost the power to divide and differentiate and are of three types- simple, complex and special. The simple tissues are parenchyma, sclerenchyma and collenchyma.

Parenchyma

• The cells have an oval or round shape.
• The cell wall is made up of hemicellulose or cellulose.
• The cell is thin-walled.
• The cells have vacuoles and very small nucleus.
• It is found in all parts of the plant.
• The protoplasm is living and dense.

Collenchyma

• Cells are long and thick-walled.
• The cell wall is made up of cellulose and pectin.
• It is the only tissue with the highest refractive index due to the presence of pectin.
• It is found in the epidermis and the vascular bundle of dicot leaf.
• The amount of chloroplast is less in the cells.
• The cells have no intercellular spaces.

Sclerenchyma

• These are dead tissues, very hard and rigid in texture.
• Cells are thick-walled with various size and shapes.
• These provide mechanical support and rigidity to the plant.

Xylem

• It transports water and nutrients from the roots to the leaves of the plant.
• It provides support to the plants.
• It is divided into-tracheids, vessels, xylem fiber, and xylem parenchyma.

Phloem

• It translocates the prepared organic food from the leaves to different parts of the plant.
• It is also known as bast.
• It is composed of sieve tubes, companion cells, phloem parenchyma, and phloem fibres.

ANIMAL TISSUES

Epithelial Tissue

Epithelial tissues form the protective covering and inner lining of the body and organs. These tissues were the first to evolve during evolution and were first formed during embryonic development. They develop from the ectoderm, mesoderm and endoderm of the embryo.

Characteristics of Epithelial Tissues

Following are the important characteristics of epithelial tissues:

1. These can be single-layered or multi-layered.
2. The tissues have the power to regenerate.
3. These are held together by gap junctions, tight junctions, zonula adheren, desmosomes, or interdigitation.
4. The plasma membrane of these cells is specialized into flagella, cilia, and microvilli.

Classification of Epithelial Tissues

The epithelial tissues can be classified as:

Connective Tissue

Connective tissues develop from the mesodermal cells of the embryo. they support and bind other tissues in the body. These are made up of three components:

• Intercellular Matrix: It is made up of mucopolysaccharide, specifically hyaluronic acid.
• Cells: The major cells include fibroblasts, adipocytes, plasma cells and mast cells.
• Fibres: Connective tissues are made up of three types of fibres, namely, collagen fibre, elastic fibre, reticular fibre.

The connective tissues perform the following functions:

1. They attach organs and tissues together.
2. They store fat in the form of adipose tissues.
3. They help in repairing tissues.
4. They prevent the organs from mechanical shocks.
5. The organs also help in defence.

Classification of Connective Tissues

The connective tissues are classified as follows:

Muscular Tissue

The muscular tissue develops from the mesoderm of the embryo. It is classified into three types:

• Cardiac
• Smooth
• Skeletal

Muscular tissue performs the following functions:

1. It helps in movement and locomotion.
2. It supports the bones and other structures.
3. It is responsible for peristalsis and parturition.

Classification of Muscular Tissue

The muscular tissue can be classified as:

Nervous Tissue

Nervous tissue makes up the peripheral and the central nervous system. It develops from the ectoderm of the embryo. It possesses the ability to initiate and transmit the nerve impulse. Its main components include: