Endoglucanase

Exo-cellobiohydrolase I

Exo-cellobiohydrolase II

β-glucosidase

Cellobiose

Glucose

Cells

TransverseSection of a log

Middle lamella

Primary wall

SecondaryWall (S3)SecondaryWall (S2)

SecondaryWall (S1)

Protein

Secondary wall

Middle lamellaPrimary wall

Cellulose

Hemicellulose

Lignin