The researchers studied how lignin and hemicelluloses change in cell walls as secondary xylem develops in Eucommia ulmoides. They used special microscopes to see where these substances were located. They found that as the secondary wall formed, lignin appeared in cell corners and middle lamella, while xylans were in the S 1 layer and xyloglucans were in the primary walls. As the S 2 and S 3 layers formed, lignin spread throughout all layers in patches. Xylans were found in the entire secondary walls, while xyloglucans stayed in the primary walls. This shows that different parts of cell walls have different hemicelluloses and lignin, creating a unique cell wall structure.