Fig. 3
From: In situ micro-spectroscopic investigation of lignin in poplar cell walls pretreated by maleic acid
SRS images of lignin resonance from a typical polar cell wall before and after maleic acid pretreatment with different acid concentrations indicated on the left. The line-scan profiles across the cell wall (dashed lines in corresponding images in the left images) show that the lignin content at secondary cell wall (SW) is more reduced than compound middle lamella (CML)