Sensory Neurons and Motor Neurons

The cells present in the soft parts of the plants are known as parenchyma cells. Parenchyma is a kind of simple tissue composed of living cells, and they help in the formation of the primary cell wall, which is a thin layer of the cell wall of the plant cell.

Cellulose and hemicellulose are the chief constituents of the primary cell wall. In addition; the parenchymatous cells are present all over the plant. They are the continuous tissues present in the roots, leaves, stems, and fruits.

Active protoplast is present in parenchymatous cells. As parenchyma is a simple issue, it is needed to produce many other specialised tissues. As far as the parenchymatous cells’ diameter is, they are isodiametric and are spherical. The presence of an isodiametric structure helps them have a thin cell wall, and hence they can overcome force and pressure all around their cell wall.

When the cell experiences pressure and force all over its side, it expands its volume to balance the pressure on all the sides. As a result, cell organelles like Golgi Bodies and Ribosomes have an abundant supply of parenchymatous cells.

As parenchyma cells are living cells, they have a meristematic region. This region remains viable even at maturity because meristematic tissues keep growing even without a stimulus.

Functions of Parenchyma cells

Following are the functions of the parenchymatous cells: 

1. Parenchymatous cells are mainly helpful and responsible for the repair of tissues.
2. As they help in the formation of the mesophyll cells, they are also helpful in photosynthesis and the exchange of gases inside the cell.
3. Parenchymatous cells also help store many substances like fats, proteins, starch, and water in the parts of the plant like roots, cotyledons, endosperm, etc.
4. They help in the secretion of various other substances.
5. They are also responsible for providing buoyancy to the cell.

Collenchyma – a descriptive view

Leaves, petioles, and young leaves have cells that are known as collenchyma cells. The structural support and strength of the plants are given by collenchyma cells. Like parenchyma cells, collenchyma cells are also living cells but have a thickly layered cell wall.

Hemicellulose, cellulose, and pectin are the chief constituents of the cell wall. When the plant experiences mechanical stress, the thick cell wall is highly affected. For example, if a plant is shaken, the collenchyma cells become thicker by 40-100% than when left unshaken.

A prominent nucleus is seen in collenchyma cells. In addition, large central vacuoles are present that help in the storage and regulation of ions and water.

Collenchyma cells are specialised in storing food and help prevent the tearing of the leaves. 

Collenchyma cells have a tubular structure and are absent in monocot plants. Instead, Collenchyma cells are mostly found in dicot plants’ leaves.

Types of Collenchyma cells

The types of collenchyma cells are:

• Angular Collenchyma cells

• Lacunar Collenchyma cells

• Lamellar Collenchyma cells

Functions of the Collenchyma cells

1. They also help in carrying out photosynthesis and manufacturing food substances.
2. They help the plants protect themselves from stretching and bending when the wind is high.
3. The mechanical support is provided by collenchyma cells to the plants. 

Differences between Parenchyma and Collenchyma cells

The differences between parenchyma and collenchyma cells are:

1. The storage, secretion, and photosynthesis in the plants are carried out by Parenchyma cells. In contrast, the Collenchyma cells help transport and distribute various essential nutrients to all the parts of the plant.
2. Parenchyma cells are distributed all over the plant like in leaves stems, whereas the collenchyma cells are seen in young stems.

3. Parenchyma is not a specialised cell, whereas collenchyma cells are highly specific and specialised.
4. The cell walls of parenchyma are relatively thin compared to collenchyma cells and have a thickly layered cell wall around them.
5. Cellulose is the chief constituent of the cell wall of parenchymatous cells, whereas collenchyma cells give pectin and cellulose as the major components in their cell wall.

Conclusion

The cells of the parenchyma and the collenchyma are highly needed in all the metabolic functions of the plant body. They are required in the major functions such as photosynthesis, storage of food particles, secretion of the important enzymes, and also provide overall strength and reliance to the plant.