Tissue culture is defined as the growth of cells and tissues of the organism out of its body. Many mediums are required to accomplish the task for example semi-solid, liquid and growth medium. Broth agar is considered as best for tissue and cell culture. It consists of nutrients, sugars, vitamins and hormones. These components in the gel make the plant to grow rapidly and produce new plantlets. Plant tissue culture is also a technique used for plants.

Historical background of tissue culture is that in 1885, Wilhelm Roux extracted small part of the medullary plate from the embryo of a chicken and cultured it. For several days he put this culture under observation and established the basis of tissue culture. Then in 1907, Ross Granville Harrison prepared a medium of clotted lymph and placed frog nerve cells in it. He observed the growth of the nerve cells in that medium. In plants tissue culture is used to increase the growth of the plants. The laboratory atmosphere is best suited for the plant tissue culture, because it s sterile and free of germs.

Steps involved in Tissue culture:-
1) First a stem cell or small part of a leave is taken which is also called as an explant. This expalnt is placed in the container of the tissue culture. Before placing the explant in the tissue culture, tissue culture should be sterilized so that no bacteria or fungus can attack the plant.
2) The tissue culture is then placed in the agar gel which is rich with nutrients, sugars and other hormones to enhance the growth of the explant.
3) Two things can occur in the tissue culture. Either the explant will start making big blobs which are called as callus or it will start producing new shoots directly from the tissue of the explant.
4) When new plantlets are produced, some of them can be removed from the tissue culture and can be placed in a new tissue culture. This way, in a limited time thousands of plants will produce.
5) Plantlet will be removed from the culture and will be transferred to the soil and they will start growing like any other traditionally growing plants.
6) Using this technique of tissue culture, laboratory plants will also be able to grow normally.

Plant tissue culture is beneficial agriculturally. By using the techniques of tissue culture, many thousands of plants can be produced in a very short time. This technique is also useful in the sense, that by using only a single parent plant, many plants can be produced. As all the procedures of tissue culture take place in the sterile environment that is why it is difficult for the germs or insects to attack the crops and growth can be increased. Plant tissue culture can also be used at cellular level. Agriculturists can observe the cells of the plants and make certain changes in the genome to make them herbicide resistant.

Like plants, animal cells can also culture. Following step take place in animal tissue culture:
1) From a particular specimen, animal cell is extracted.
2) A special kind of medium is required for the animal tissue culture. Animal cell or tissue is placed in the medium under aseptic environment.
3) For the animal tissue culture, specific temperature is required and cells are grown in the culture. For example, the temperature required for the human cells to culture is 37 degrees which is the normal body temperature.
4) Carbon dioxide is also required.

There is a difference of animal cells culture than plants tissue culture. Undergoing the limited number of cell cycles, animal cells begin to degrade. When the animal cell culture is produced in the medium, there is a lot of need of changing the medium otherwise animal cells will not grow properly. There is difficulty of growing the animal cell and tissue culture because unlike plants which need nutrients and other components, animal cells need vitamins, proteins and other body components which are slightly difficult to provide to the medium.

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