Difference Between Pits and Plasmodesmata

The key difference between pits and plasmodesmata is that pits are the thin regions of the plant cell wall that facilitate communication and exchange of substances with neighbouring cells while plasmodesmata are microscopic intercellular bridges that connect the cytoplasm of neighbouring cells with each other, facilitate communication and transport of materials between plant cells.

Plant cells have two outer coverings as the plasma membrane and cell wall. The cell wall is a rigid structure which maintains the shape of the plant cell. It also provides strength and structural support to the cell. Plant cells communicate with each other, and they exchange substances between them. Pits and plasmodesmata help plant cells for these functions. Pits are the thin regions of the cell walls that are abundant with plasmodesmata. Plasmodesmata are the cytoplasmic bridges that connect the cytoplasms of neighbouring cells. Both pits and plasmodesmata facilitate the transportation of substances between plant cells and communication between them.

CONTENTS

1. Overview and Key Difference
2. What are Pits 
3. What are Plasmodesmata
4. Similarities Between Pits and Plasmodesmata
5. Side by Side Comparison – Pits vs Plasmodesmata in Tabular Form
6. Summary

What are Pits?

Pits are thin regions or narrow areas of the cell wall of plant cells. In fact, they are the depressions of the plant cell wall. Pits mediate the communication between adjacent cells. They also facilitate the transport of substances between cells via plasmodesmata. Thus, plasmodesmata are abundant in pits. Usually, two pits of the neighbouring cells are located opposite to each other. Therefore, a pit pair can always be seen in plant cells.  Each pit has a pit cavity. Then the two pit cavities of the two opposite pits separate from a pit membrane. The space found inside a pit is the pit chamber.

Pits can be simple pits or bordered pits. A bordered pit is different from a simple pit as it has a secondary wall over the pit cavity. Parenchyma cells, medullary rays, phloem fibres, companion cells, and tracheids of several flowering plants have simple pits while vessels of many angiosperms and tracheids of many conifers have bordered pits abundantly. In addition to simple pits and bordered pits, some plants have half bordered pits, blind pits and compound pits.

What are Plasmodesmata?

Plasmodesmata are microscopic channels that connect the cytoplasm of neighbouring plant cells with each other. They are intercellular cytoplasmic bridges. They penetrate into both primary and secondary cell wall of the plant cell and create a passage between two cells to facilitate the transportation of substances from one cell to other and communication between them.

Structurally, plasmodesmata are tube-like structures. There are desmotubules in the space of plasmodesmata. Desmotubules consist of a tightly packed endoplasmic reticulum. Moreover, there is a cytoplasmic sleeve between the membrane and the desmotubules. It is a fluid-filled space which is an extension of the cytosol.  Transfer of molecules occurs via the cytoplasmic sleeve. Small molecules diffuse through the sleeve without the use of energy. The sleeve contains protein fibres such as actin and myosin, which provide contractile forces to transport substances across the plasmodesmata.

Plasmodesmata are present in almost all plant cells. They are abundant in pits. Plasmodesmata are vital in nutrient transportation via the vascular tissue.

What are the Similarities Between Pits and Plasmodesmata?

• Both pits and plasmodesmata are present in plant cells.
• Plasmodesmata are abundant in pit membranes.
• They facilitate the transport of substances between cells and the communication between them.

What is the Difference Between Pits and Plasmodesmata?

Pits and plasmodesmata help plant cells to communicate with each other and transport substances between them. Pits are thin areas of the cell wall. In contrast, plasmodesmata are the cytoplasmic bridges that transverse in the cell wall. So, this is the key difference between pits and plasmodesmata.

Summary – Pits vs Plasmodesmata

Pits are thin areas of plant cell walls. Cells communicate and exchange substances through the pits. In contrast, plasmodesmata are microscopic bridges that connect the cytoplasms of neighbouring plant cells. Plasmodesmata are dense in the pits. Plasmodesmata also facilitate the transportation of substances between the cells and the communication between them. So, this is the summary of the difference between pits and plasmodesmata.

Reference:

1. Ross E. Sager, Jung-Youn Lee. “Plasmodesmata at a Glance.” Journal of Cell Science, The Company of Biologists Ltd, 1 June 2018, Available here.
2. “Pit Pairs: Structure and Types: Biology (777 Words).” Your Article Library, 22 Feb. 2014, Available here.

Image Courtesy:

1. “Image from page 321 of “Botany of the living plant” (1919)” By Internet Archive Book Images (No known copyright restrictions) via Flickr
2. By Jackacon, vectorised by Smartse – Apoplast and symplast pathways.gif (Public Domain) via Commons Wikimedia