The three-dimensional arrangement of intermediate filaments in Romney wool cortical cells

Caldwell, Jonathan P.; Mastronarde, David N.; Woods, Joy L.; Bryson, Warren G.

doi:10.1016/j.jsb.2005.07.002

Cited by 39 publications

(36 citation statements)

References 24 publications

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“…This is in contrast to many reports of a strong correlation between the ratio of para-cortical to ortho-cortical cell areas and fibre crimp, but is in keeping with other studies that show a decrease in fibre crimp as the proportion of para-cortical cells increases with increasing nutrition (Campbell et al, 1972). Other studies ascribing differences in fibre curl to differences in the composition (Plowman et al, 2000) or structural arrangements of intermediate filaments (Caldwell et al, 2005), probably reflect secondary effects of differential keratinisation, but are not directly responsible for fibre bending. Hynd, Edwards, Hebart, McDowall and Clark …”

Section: Discussionsupporting

confidence: 83%

“…The biological and physicochemical basis of fibre bending has been the subject of considerable speculation over many decades. Most include one or more of the following mechanisms or associations: differing ratios and composition of ortho-, meso-and para-cortical cells (Horio and Kondo, 1953;Fraser and Rogers, 1954); rotation of the inner root sheath and fibre cuticle around the fibre cortex, thereby imparting torsion to, and shortening of, the cortical cells (Nagorcka, 1981); different spatial arrangements of the intermediate filaments within the cortical cells (Caldwell et al, 2005;Kajiura et al, 2006); and differences in the expression of keratins and keratin-associated proteins in cortical cells of high-and low-fibre crimp (Plowman et al, 2000). In wool-producing sheep there is an association between the degree of follicle curvature and fibre crimp frequency (Nay and Johnson, 1967).…”

Section: Introductionmentioning

confidence: 99%

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Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

Hynd

Edwards

Hebart

et al. 2009

Animal

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Crimp, a distinguishing feature of sheep fibres, significantly affects wool value, processing and final fabric attributes. Several explanations for fibre bending have been proposed. Most concentrate on relative differences in the physicochemical properties of the cortical cells, which comprise the bulk of the fibre. However, the associations between cortical properties and fibre crimp are not consistent and may not reflect the underlying causation of fibre curvature (FC). We have formulated a mechanistic model in which fibre shape is dictated primarily by the degree of asymmetry in cell supply from the follicle bulb, and the point at which keratinisation is completed within the follicle. If this hypothesis is correct, one would anticipate that most variations in fibre crimp would be accounted for by quantitative differences in both the degree of mitotic asymmetry in follicle bulbs and the distance from the bulb to the point at which keratinisation is completed. To test this hypothesis, we took skin biopsies from Merino sheep from sites producing wool differing widely in fibre crimp frequency and FC. Mitotic asymmetry in follicle bulbs was measured using a DNA-labelling technique and the site of final keratinisation was defined by picric acid staining of the fibre. The proportion of parato ortho-cortical cell area was determined in the cross-sections of fibres within biopsy samples. Mitotic asymmetry in the follicle bulb accounted for 0.64 ( P , 0.0001) of the total variance in objectively measured FC, while the point of final keratinisation of the fibre accounted for an additional 0.05 ( P , 0.05) of the variance. There was no association between ortho-to para-cortical cell ratio and FC. FC was positively associated with a subjective follicle curvature score ( P , 0.01). We conclude that fibre crimp is caused predominantly by asymmetric cell division in follicles that are highly curved. Differential pressures exerted by the subsequent asymmetric cell supply and cell hardening in the lower follicle cause fibre bending. The extent of bending is then modulated by the point at which keratinisation is completed; later hardening means the fibre remains pliable for longer, thereby reducing the pressure differential and reducing fibre bending. This means that even highly asymmetric follicles may produce a straight fibre if keratinisation is sufficiently delayed, as is the case in deficiencies of zinc and copper, or when keratinisation is perturbed by transgenesis. The model presented here can account for the many variations in fibre shape found in mammals.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

Hynd

Edwards

Hebart

et al. 2009

Animal

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“…The ortho-cortex macrofibril, by contrast, is a clearly distinct structure, being more separated from its neighbours, and the intermediate filaments appear as if wound helically around a central core, the helix tilt angle increasing radially from the centre. Recent TEM tomographic studies have clarified and quantified the geometry of the IF arrangements in these cell types (Caldwell et al, 2005;Harland et al, 2010). The superficial similarity between wellknown mesophase textures and the IF arrangements in the cell types is made clear in Fig.…”

Section: Differentiation In Trichocytesmentioning

confidence: 91%

“…A key challenge to the mesophase model is to rationalise the different types of macrofibril structural development observed in keratin fibre cortical cells; namely the differentiations described as ortho-, meso-, and para-cortex (Caldwell et al, 2005;Bryson et al, 2009;Whiteley and Kaplin, 1977;Harland et al, 2010;Orwin et al, 1984). In some animal fibres, notably fine merino wool, cell types are highly differentiated with respect to macrofibril structure, with para-cortex and ortho-cortex typically having their own exclusive type of macrofibril (Harland et al, 2010).…”

Section: Differentiation In Trichocytesmentioning

confidence: 99%

“…The association of the observed structural motifs with liquid crystal mesophases, of both untwisted (nematic -perhaps, more correctly, twistless cholesteric) or double-twist character is portrayed in Fig. 4, which compares the fibrillar structures observed in different cortical cell types by electron tomography (Caldwell et al, 2005) with the idealised structures of mesophases (de Gennes and Prost, 1993;Crooker, 2001;Livolant, 1991).…”

Section: Introductionmentioning

confidence: 99%

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A concerted polymerization-mesophase separation model for formation of trichocyte intermediate filaments and macrofibril templates. 1: Relating phase separation to structural development

McKinnon¹,

Harland

2011

Journal of Structural Biology

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The biology of human hair: A multidisciplinary review

Koch

Tridico²,

Bernard

et al. 2019

American J Hum Biol

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In the last century, human scalp hair morphology has been studied from multiple, and sometimes mutually exclusive, perspectives by anthropologists, biologists, geneticists, forensic scientists, and cosmetic scientists. Here, we review and synthesize historical and current research on hair to better understand the scientific basis and biological implications of hair microstructure and morphology. We revisit the origins of existing nomenclature regarding hair morphology and classifications, discuss the currently recognized limitations to hair analysis within the varied scientific disciplines studying hair, point out aspects of hair biology that remain unknown, and the great potential for integrating these diverse perspectives and expertise in future scientific investigations, while highlighting the benefits of combining nondestructive microscopical analysis with chemical and genomic analyses for explicating hair biology. Further, we propose consensus terminology for root growth stages through descriptions and images that will aid in the morphological and microscopical analysis of human scalp hair, thereby reducing confusion and the promulgation of inaccurate information that is presently in the literature.

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The three-dimensional arrangement of intermediate filaments in Romney wool cortical cells

Cited by 39 publications

References 24 publications

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

A concerted polymerization-mesophase separation model for formation of trichocyte intermediate filaments and macrofibril templates. 1: Relating phase separation to structural development

The biology of human hair: A multidisciplinary review

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