\citet{wardrop1965} commented that a tensile stress generated in the cellulose transitioning into a crystalline state could be the explanation for cells contracting during the formation of the secondary wall. Cellulose contraction aligned well with the observation of the G-layer (which has a very low MFA) being common in a number of tension wood producing species, and also give the ability for low MFA normal wood to contract. \citet{Bamber1979} further argued cellulose contraction claiming turgor pressure in normal wood cells remained high enough that the cells did not contract before the lignin was deposited, once/during lignin deposition the cellulose became crystalline and shrunk, causing the cell to become shorter, the mechanism for tension wood was sugested to be essentially the same. Compression wood on the other had was explained by the cellulose being laid down and then the turgor pressure decreasing, causing the cell to contract before lignin was deposited. In turn the cellulose was under compression, resulting in the tendency for the compression wood cells to expand. Later \citet{bamber2001general} argues that the cellulose is laid down in a compressed or extended state to account for both compression wood and tension wood respectively.