Parenchyma Cells

Definition Of Parenchyma Cells

Parenchyma cells are basic plant cells that have thin and flexible walls with a large central vacuole. They are versatile and thus play a very important role in many different functions of plants, from storage of nutrient reserves to wound healing, and photosynthesis. Stem parenchyma cells can divide and differentiate to produce new tissues, so they are of great importance in the development and regeneration of plant tissues.

In the 19th century, early botanical studies on plant anatomy first discovered the existence of the parenchyma cells. The first experimental works on these types of cells by scientists like Karl Friedrich Wilhelm Schimper and Matthias Schleiden enabled the identification of the wide distribution and the capacity to engage in storage and metabolic activities in plant tissues. These studies thus laid the foundation for explaining the various functions of the parenchyma cells in Plant Biology

Structure Of Parenchyma Cells

The structure of parenchyma cells is defined below:

Cell Shape And Size

The parenchyma cells normally are isodiametric or polyhedral, though at times more elongated. In size, these cells may be quite variable due to their position and the role carried by them in the plant. A fairly big central vacuole is usually found in these cells that contributes towards the development of turgor pressure, and the maintenance of the general cell shape.

Cell Wall Characteristics

The cell walls of these parenchyma cells are thin and flexible, basically made of cellulose. This thinness thus allows more expansion and contraction, which allows for their varying roles. Compared to other plant cell types, there are no secondary cell walls in the parenchyma cells.

Cytoplasmic Features

The cytoplasm of the parenchyma cell is developed well with many organelles, hence containing a large central vacuole, plastids, which include chloroplasts in the chlorenchyma, and inclusions. The presence of plastids is useful in photosynthesis and storage.

Chlorenchyma

A specialised form of parenchyma in which the cells are large, and are actively taking part in the process of photosynthesis. The cells have a lot of chloroplasts. Such cells are found in the green tissues of a plant, more so in the leaves that are well adapted to trap light energy intended for photosynthesis.

Aerenchyma

A spongy parenchyma comprising large air spaces known as lacunae, allows an exchange of gases, especially in aquatic plants or plants growing under waterlogged conditions. This tissue reinforces buoyancy and aids in the diffusion of gases between tissues contained below water and the atmosphere.

Storage Parenchyma

The storage parenchyma cells will store nutrients in the form of starch, oils, and proteins. They are themselves located in the roots and tubers of plants and the endosperms of seeds. Sugars and other energy sources in storage support plant growth including things like fiber for structural support and seeds for another generation.

Functions Of Parenchyma Cells

The functions are given below:

Photosynthesis

In chlorenchyma cells, the parenchyma are significant cells for photosynthesis through the absorption of sunlight and conversion to chemical energy. They contain chloroplasts that assist the cells in the production of sugars and oxygen to be used in supplying energy to the plant.

Storage

These cells store carbohydrates, lipids, and proteins. This type of storage in these parenchyma cells greatly aids plant survival, especially in the accumulation of energy reserves that can be mobilised during times of stress.

Secretion

Some of the parenchyma cells become specialised in secreting various substances like essential oils, resins, and mucilages. These secretions can be protective, be used as attractants for pollinating agents, or in defence after herbivores and pathogens attack the plant.

Wound Healing And Regeneration

Parenchyma cells facilitate wound healing because of their ability to divide and form new tissues to substitute for the damaged ones. Due to the ability of parenchyma to divide, the cells proliferate and differentiate into other types of cells, hence healing the damaged plant tissues and promoting their health and resistance.

Transport

Even though parenchyma cells do not relate as main workers for the operation of long-distance transport, they allow nutrients and water to pass through them in the tissues. More extensive connections between cells with thin cell walls enable the diffusion of substances between them to support the overall plant metabolism and growth.

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