Diagram of Plant Cell Wall – Layers Between Two Cells

All 11 parts on the diagram

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Between two cells 7

Middle lamella The layer between two neighboring cells. It is rich in pectin and cements their walls together.
Primary cell wall The first wall a cell makes. It is thin and flexible, so it can stretch while the cell grows.
Secondary cell wall A thick layer laid down inside the primary wall. Some cells add it once they stop growing, and lignin often stiffens it.
Plasma membrane The living boundary of the cell. It lies just inside the wall and lines each pit.
Plasmodesma A channel of cytoplasm through the wall. It joins the two cells, and the plural is plasmodesmata.
Pit A spot with no secondary wall. The pits of two neighbors line up as a pit pair.
Cytoplasm The living contents of the cell inside the membrane. It runs on through each plasmodesma into the next cell.

Inside the wall 4

Cellulose microfibril A long, stiff thread of many cellulose molecules. Microfibrils carry the pull on the wall.
Hemicellulose Shorter, branched molecules that tie one microfibril to the next.
Pectin The soft matrix of the primary wall. The microfibrils and their tethers sit in it.
Lignin A hard filling in many secondary walls. It stiffens and waterproofs them, and wood is full of it.

How this list was compiled: Every name was checked on 2026-10-01 and kept only where two independent sources use it. (1) Wikipedia, text only: Cell wall, https://en.wikipedia.org/wiki/Cell_wall ; Middle lamella; Secondary cell wall; Plasmodesma; Pit (botany). (2) USDA Forest Service, Forest Products Laboratory, Wood Handbook (General Technical Report FPL-GTR-190, 2010), chapter 3, Structure and Function of Wood, https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr190/chapter_03.pdf : the middle lamella, the primary wall, the secondary wall, pits, cellulose microfibrils, hemicelluloses, pectin and lignin. (3) Kimball's Biology Pages, The Plant Cell, https://www.biology-pages.info/P/PlantCell.html : primary and secondary cell walls, plasmodesmata, the plasma membrane, cellulose fibrils, pectin and lignin. (4) The American Heritage Dictionary of the English Language, fifth edition, https://www.ahdictionary.com/ : plasmodesma, pit (the botany sense), hemicellulose, lignin. Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

A plant cell wall is built in layers. This diagram of the plant cell wall enlarges the stretch where two cells meet, then goes inside the wall to show the cellulose rods and what fills the space round them.

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Read the layers from the middle outward

The middle lamella is the glue between the two cells. Each cell lays its primary wall against it, and some cells then add a thick secondary wall inside that. The plasma membrane lies inside the wall.

Where the wall lets things through

A pit is a gap in the secondary wall, so only the thin layers are left there. A plasmodesma is a channel of cytoplasm through the wall from one cell into the next.

Primary means made first, not innermost: the primary wall lies nearer the middle lamella than the secondary wall.

Questions and answers

What is the plant cell wall made of?

Mostly cellulose, gathered into long threads called microfibrils. Shorter hemicellulose molecules tie the microfibrils together, and the whole net sits in a soft matrix of pectin. Many secondary walls also hold lignin, which makes them stiff.

What is the difference between the primary and secondary cell wall?

The primary wall is thin and flexible, and the cell makes it while it is still growing. The secondary wall is thicker and is laid down inside the primary wall after growth stops. Not every plant cell makes one.

What is the middle lamella?

It is the layer between the walls of two neighboring plant cells. It is rich in pectin and holds the two cells together, much as mortar holds bricks.

What are plasmodesmata?

They are tiny channels that pass through the walls of plant cells. Each one is lined by the plasma membrane and filled with cytoplasm, so neighboring cells stay connected. One channel is a plasmodesma.