Wood materials are nowadays being viewed with increasing interest, as a green resource. Its utilization in new types of applications is also highly desired. Thus a better understanding of the wood ultrastructure and how the wood components are interacting in building up its properties is highly demanded. In the wood, the cellulose fibril aggregates dominates properties especially along the grain why the contribution from the other wood polymers and its role in the arrangement of the cell wall structure is often neglected. However their importance both in affecting transverse fiber properties and in their role as a spacer affecting cellulose aggregation during processing cannot be neglected. As the cellulose microfibrils make up a highly irregular lenticular three-dimensional structure the role of the matrix polymers in-between may be viewed in different ways. The understanding of the load bearing capacities of the lignin in different structural elements may be a key factor.