Fiber bilaterally structured

Kassenback, P., Incidence of Bilateral Structure of Cotton Fibers, in First International Symposium on Cotton Textile Research, Paris, 1969, p. 455. 

An alternative and more likely explanation considers the bilateral structure of some keratin fibers like wool. A helical fiber will arise if opposite halves of the fiber grow at different rates or if opposite halves contract to different extents during drying. This is analogous to the way a bilateral thermostat bends with changes in temperature. 

Early studies on the fine structure of specialty animal fibers involved differential staining using dyestuffs or heavy metals, and subsequent observations were made using light microscopy. By means of these techniques, vicuna fiber was shown to have a bilateral structure [318], and mohair fiber, predominantly ortho- with some paralike material [319] (see Sections 5.2.2 and 5.2.3). Bilateral structures are also observed when wool, cashmere, camel, and alpaca (but not mohair) are treated with sodium hydroxide and examined by means of polarized light [297]. 

Camel fibers from the same fleece can exhibit both bilateral and random cell arrangements. Similar observations have been made for yak fibers, which tend to consist mainly of ortho- and mesolike cells [296]. Vicuna and guanaco exhibit bilateral structure, whereas llama and alpaca do not [296]. 

Good bulk and crimp stability can be obtained with bicomponent fibers (also known as conjugated fibers, twin fibers, or fibers of bilateral structure). The two components may lie side by side, and have a nucleus-mantle structure or a matrix-fibrillar (M/F) structure (Figure 12-10). The M/F fibers are known as matrix fibers in the United States and not as bicom-... 

TEM studies of thin transverse fiber sections show that the cortical structure of cashmere is considerably different from that of fine wool [296,311,320]. Australian and Chinese cash-mere fibers display both bilateral symmetry and random cell arrangements, not only in cashmere fibers from different samples but also in fibers from the same fleece [296,311], whereas fine wool fiber exhibits bilateral asymmetry only. The variation in cortical structure among fibers from the same cashmere fleece suggests that different mechanisms may be involved in fiber formation. Cashmere cortex is composed predominantly of ortholike and mesolike cells, whereas fine wool is composed predominantly of ortho- and paracortical cells arranged bilaterally. Because of the variations observed, many transverse sections need to be examined before definitive statements can be made about the physical structure of fiber from a given cashmere sample. 

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