Meristematic Tissue vs Permanent Tissue
With the evolution, plant body has grown larger and become more complex. Because of their complexity, division of labor occurs and groups of cells are assigned to perform a particular function in multicellular organisms. A group of cells that perform a common function and have a common origin is known as tissue. A collection of tissues together forms an organ within a plant body. Normally, a multicellular plant body has similar or dissimilar type of tissue which performs similar or dissimilar functions. Tissues can improve the organization of the body by forming organ systems. It can also increase the efficiency of the body functions by decreasing the workload of individual cell. The plant tissues are broadly categorized into two groups based on their dividing capacity; namely, Meristematic and Permanent tissues.
Meristematic Tissue (Growth Tissues)
Meristematic tissue is a group of living cells with continuous power of division. In plants, the growing regions are restricted to certain areas. These regions are called meristematic regions (ex: – root tip, shoot tip and cambium) in which meristematic tissues are located. These tissues are also called growth tissues due to their dividing ability, hence increasing length and thickness of the plant.
The meristematic tissue can be further dived into three categories based on the position in the plant body. They are apical meristem, lateral meristem (cambium), and intercalary meristem. Apical meristem is the primary meristem from which other meristems are derived, and they increase the length of plants. Cambium helps to increase the thickness or girth of the stem and root. Intercalary meristem is responsible for the longitudinal growth by adding primary tissues.
The permanent tissues are derived from meristematic tissues and lately differentiated into different tissues. The cells in these tissues may lose the ability of division temporarily or permanently, but in certain circumstances such as wound healing and secondary growth and if the cells are alive, they may regain their power of division.
These tissues are divided into primary permanent tissues and secondary permanent tissues, on the basis of origin. They can also put into three categories depending on their structure and functions. They are simple tissues, complex tissues and special tissues. A group of similar cells that perform a common function is defined as a simple tissue. Examples for simple tissues are parenchyma, collenchymas and sclerenchyma. Complex tissues or compound tissues are made up of a different kind of cells, and they perform a common function. Examples are vascular tissues such as phloem and xylem. Special tissue or secretory tissue is made up with cells that can secrete certain products (enzymes, hormones etc).
Differences between Meristematic and Permanent Tissues:
• The major difference is that the cells of meristematic tissue divide repeatedly while the cells of permanent tissue have no such ability.
• The cells of permanent tissue are derived from the meristematic tissue.
• Permanent tissue is made up with differentiated cells from the meristematic cell, but the cells of meristematic tissues remain undifferentiated.
• The cells of meristematic tissue are small and have a similar structure with thin cellulose cell walls. The cells of permanent tissues are larger and have a definite shape and size. The cell walls may be thin or thick in permanent tissue.
• The cells are compactly arranged so that among cells, there are no intercellular spaces in meristematic tissues, but in permanent tissue, the cells may be arranged compactly or loosely and often have intercellular spaces between cells.
• Unlike permanent tissue, meristematic tissue is restricted to certain regions in a plant body.
• Usually vacuoles are absent in cells of meristematic tissue. The cells of permanent tissues have large vacuoles.
• Unlike in the cells of permanent tissue, metabolism rates are very high in the cells of meristematic tissue.
• The crystals and other inorganic inclusions are often present in permanent tissues while inorganic inclusions are absent in meristematic tissue.
• Each cell of meristematic tissue has a dense cytoplasm and a large nucleolus while the cells of permanent tissue have small nucleus.
• The function of the meristematic tissue is to help in the growth. Permanent tissue helps in protection, photosynthesis, conduction, support etc.
• Meristematic tissue has live cells while permanent tissue may have living or dead cells.