The chemical composition of wool 7. Separation and analysis of orthocortex and paracortex

Chapman, GV; Bradbury, J. H.

doi:10.1016/0003-9861(68)90212-9

Cited by 22 publications

(21 citation statements)

References 15 publications

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“…In order to check on the relative rates of breakdown of orthocortical cells and paracortical cells during ultrasonication, gold-stained orthocortical cells and paracortical cells were prepared [11]. They were subjected separately to ultrasonication in formic acid and the percentage of intact cortical cells remaining in the dispersion was measured microscopically bv cell count.…”

Section: Methodsmentioning

confidence: 99%

“…To elucidate the chemistry of this complex structure, it is clearly necessary to separate the various histological components by methods which are as mild as possible, prior to amino acid analysis, solubilization and separation of soluble proteins, etc. Clean separations and amino acid analyses were obtained initially for cuticle and cortical cells [2, 4J but [9,11,16], and for the central core or medulla [6, 10J of coarse keratin fibers.…”

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The Chemical Composition of Wool

Bradbury

Peters

1972

Textile Research Journal

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Macrofibrils of wool fibers are prepared by ultrasonication of cortical cells in formic acid and are separated from other particles by differences between their rates of settling in a column of ethanol. The macrofibrils are observed by light microscopy and scanning electron microscopy to be about 10 μm long and 0.3 μm diameter and are made up of finer, fibrous filaments. The amino acid analysis of macrofibrils is essentially the same as that of cortical cells, which have been subjected to a similar ultrasonication treatment.

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Section: Methodsmentioning

confidence: 99%

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The Chemical Composition of Wool

Bradbury

Peters

1972

Textile Research Journal

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“…Another division of the cortex is that of the ortho-and paracortex in some wools. Chapman and Bradbury (1968) concluded that the differences between the two areas are based on (1) the configuration of the microfibrils, (2) the microfibril to matrix ratios, and (3) possible variation in amino acid sequences in the two areas.…”

Section: An Analysis Of Hair Structure and Its Phylogenetic Implicatimentioning

confidence: 99%

An Analysis of Hair Structure and Its Phylogenetic Implications among Heteromyid Rodents

Homan

Genoways

1978

Journal of Mammalogy

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“…Hence the precise component producing the detected x-rays cannot be determined. In the STEM, the very thin sections required for maximum resolution of components give very low intensities of x-rays because of the much smaller specimen volumes.The merino wool fiber consists of an inner cortex and a peripheral region known as the cuticle [3,15].The cortex can be differentiated into orthocortical and paracortical cells on the basis of the denser staining of the orthocortex by basic dyes, acid dyes, and phosphotungstic acid, and by salts of lead, mercury, silver and gold [2,5,10,12,16,21 ]. Several attempts have been made to determine the origin in the intact wool fiber of various proteins isolated as soluble extracts [3,6].…”

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“…The cortex can be differentiated into orthocortical and paracortical cells on the basis of the denser staining of the orthocortex by basic dyes, acid dyes, and phosphotungstic acid, and by salts of lead, mercury, silver and gold [2,5,10,12,16,21 ]. Several attempts have been made to determine the origin in the intact wool fiber of various proteins isolated as soluble extracts [3,6].…”

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Using Electron Microscopy and X-Ray Microanalysis to Study Wool Morphology and Composition

Carr

Holt

Drennan

1986

Textile Research Journal

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Energy dispersive x-ray analysis has been used in combination with scanning electron microscopy and scanning transmission electron microscopy to investigate the distribution of both cystine and tyrosine in the morphological components of wool fiber. The technique has also been used to show that the zirconium in Zirpro treated wool is deposited evenly throughout the fiber.The technique [8] of scanning electron microscopy (SEM) with an energy dispersive x-ray microanalysis system (EDS) involves irradiating a sample with a fine beam of electrons. When the electron beam impinges on the specimen, the primary electrons can be reflected or, alternatively, can produce secondary electrons or x-rays. The primary and secondary electrons produce the image of the sample, whereas the characteristic xrays can be used to determine the nature and concentration of the elements present in the specimen. In scanning transmission electron microscopy (STEM), the x-rays produced by the electron beam can be analyzed to give the same information, but the image of the specimen is formed by the transmitted electrons.In any study of biological materials using electron microscopy with EDS, a compromise has to be made with regard to specimen thickness. Infinitely thick specimens, which can be studied with the SEM, give the maximum amount of x-rays, but in a heterogeneous specimen, the distribution of components within the specimen is unresolved in the electron image. Hence the precise component producing the detected x-rays cannot be determined. In the STEM, the very thin sections required for maximum resolution of components give very low intensities of x-rays because of the much smaller specimen volumes.The merino wool fiber consists of an inner cortex and a peripheral region known as the cuticle [3,15].The cortex can be differentiated into orthocortical and paracortical cells on the basis of the denser staining of the orthocortex by basic dyes, acid dyes, and phosphotungstic acid, and by salts of lead, mercury, silver and gold [2,5,10,12,16,21 ]. Several attempts have been made to determine the origin in the intact wool fiber of various proteins isolated as soluble extracts [3,6]. These studies involve disruption of the wool fiber by ultrasonication or by repeated freeze-thawing in formic acid [ 11 ], separation of the cortical cells by centrifugation in an organic medium of appropriate density, and protein and amino acid analyses of the separated cell fractions. One possible disadvantage of this technique is that the severity of the procedures required to disrupt the wool 6ber may lead to degradation of the proteins or loss of material from the cells into the solvent.K,assenbeck et al. [ 13] have attempted to overcome these problems by using SEM and EDS to determine the sulfur distribution in intact wool fiber sections. Sulfur content was found to vary from 4.3% to 2.9% across the fiber, and the high and low sulfur regions were assigned to paracortex and orthocortex, respectively, on the basis of results obtained by other workers from stud...

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The chemical composition of wool 7. Separation and analysis of orthocortex and paracortex

Cited by 22 publications

References 15 publications

The Chemical Composition of Wool

The Chemical Composition of Wool

An Analysis of Hair Structure and Its Phylogenetic Implications among Heteromyid Rodents

Using Electron Microscopy and X-Ray Microanalysis to Study Wool Morphology and Composition

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