Middle lamella

The middle lamella is a pectin layer which cements the cell walls of two adjoining cells together. Plants need this to give them stability and so that they can form plasmodesmata between the cells. It is the first formed layer which is deposited at the time of cytokinesis. The cell plate that is formed during cell division itself develops into middle lamella or lamellum. The middle lamella is made up of calcium and magnesium pectates.^[1]In a mature plant cell it is outermost layer of cellwall.

In plants, the pectins form a unified and continuous layer between adjacent cells. Frequently, it is difficult to distinguish the middle lamella from the primary wall, especially in cells that develop thick secondary walls. In such cases, the two adjacent primary walls and the middle lamella, and perhaps the first layer of the secondary wall of each cell, may be called a compound middle lamella. In multicelluar organisms, when middle lamella dissolves, the cells get isolated from each other.^[2] If enzymes degrade the middle lamella, the adjacent cells will separate.

References

2.Telugu Akademi Hyderabad "Intermediate first year Botany"