Plant Cell Walls - 9  
311 Syllabus

Wall Architecture - Varies Cell - Cell & Wall to Wall but some general rules exist.

Variations in Cell Wall Thickness can be observed in this section from a Sunflower Stem. However, there are definite areas which have similar wall traits.

Primary vs Secondary Walls

Primary Walls are Formed by Growing Cells

They tend to be Thin & Uniform.

The Cellulose Microfibrils have a Random Distribution.

Secondary Walls are Formed after Growth Stops

They are usually Thick, Organized, Multilayered &

contain Lignin.

The Cellulose Microfibrils have a highly ordered appearance.

The thin Primary Walls of this cell are almost invisible. the light oval areas are Pits.

These Cells are called Fibers. They have thick Secondary Walls. The Middle Lamella is visible as the Yellow Lines that occur where adjacent Cell Walls meet. The red color indicates the presencre of   Lignin in the Secondary Walls.

The Middle Lamella is the Interface of adjacent Cells.

High in Pectins

Can become Lignified