Radial microfibril arrangements in wood cell walls

Abstract

Main conclusion TEM and AFM imaging reveal radial orientations and whorl-like arrangements of cellulose microfibrils near the S1/S2 interface. These are explained by wrinkling during lamellar cell growth. Abstract In the most widely accepted model of the ultrastructure of wood cell walls, the cellulose microfibrils are arranged in helical patterns on concentric layers. However, this model is contradicted by a number of transmission electron microscopy (TEM) studies which reveal a radial component to the microfibril orientations in the cell wall. The idea of a radial component of the microfibril directions is not widely accepted, since it cannot easily be explained within the current understanding of lamellar cell growth. To help clarify the microfibril arrangements in wood cell walls, we have investigated various wood cell wall sections using both transmission electron microscopy and atomic force microscopy, and using various imaging and specimen preparation methods. Our investigations confirm that the microfibrils have a radial component near the interface between the S1 and S2 cell wall layers, and also reveal a whorl-like microfibril arrangement at the S1/S2 interface. These whorl-like structures are consistent with cell wall wrinkling during growth, allowing the radial microfibril component to be reconciled with the established models for lamellar cell growth.

Bionic ordered structured hydrogels: structure types, design strategies, optimization mechanism of mechanical properties and applications

“…36,47,48 The arrangement of microfibers in different types of wood can vary significantly, affecting cell growth and distribution within trees, subsequently influencing the mechanical properties of wood. [49][50][51] Besides plants, animals also have ordered lamellar structures in their biological tissues. For instance, the soft membrane tissue of lobster exhibits great toughness and damage resistance due to the chitin fibers' orderly arrangement, forming a multi-level ordered structure.…”