scholarly journals Studies on the Follicle Bulb of Fibres I. Mitotio and Cellular Segmentation in the Wool Follicle With Reference to Ortho·and Parasegmentation

1964 ◽  
Vol 17 (2) ◽  
pp. 521 ◽  
Author(s):  
EB Fraser
Keyword(s):  
Mitotic Activity ◽  
Density Gradient ◽  
Cell Layer ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Wool Follicle

IThere is a gradient in the density of cells in mitosis which decreases in a proximodistal direction. Mitotic activity ends at a height one cell layer above the apex of the papilla. The decreasing mitotio density gradient commences at a level, in all bulbs, coincident with the proximal limit of differentiation of Henle's layer of the inner root sheath.

scholarly journals Cell Differentiation in the Lower Outer Sheath of the Romney Wool Follicle: A Companion Cell Layer

1971 ◽  
Vol 24 (4) ◽  
pp. 989 ◽  
Author(s):  
DFG Orwin
Keyword(s):  
Cell Layer ◽  
Skin Surface ◽  
Morphological Evidence ◽  
Companion Cell ◽  
Outer Root Sheath ◽  
Outer Sheath ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Wool Follicle ◽  
Outer Root Sheath Cells

Morphological evidence is presented showing that, in the Romney wool follicle, the layer of cells in the outer root sheath lying next to Henle's layer differentiates in the bulb as a separate and distinct layer from other outer root sheath cells. The term "companion cell layer" is suggested for this layer. Its possible role in the movement of the inner root sheath toward the skin surface is discussed.

Wool follicle morphology and cell proliferation in New Zealand Romney sheep: a seasonal comparison of fleeceweight-selected and control rams

1994 ◽  
Vol 45 (4) ◽  
pp. 769 ◽  
Author(s):  
SA Holle ◽  
PM Harris ◽  
AS Davies ◽  
MJ Birtles
Keyword(s):  
New Zealand ◽  
Three Dimensional ◽  
Dermal Papilla ◽  
Proliferating Cells ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Dimensional Measurements ◽  
Wool Follicle ◽  
Seasonal Influences ◽  
And Control

Effects of selection for high fleeceweight in the New Zealand Romney sheep were investigated in relation to the morphology of individual follicles and changes in the germinative cell population of the follicle bulb. Two-year-old Romney rams, 10 from each of two selection lines (Massey University fleeceweight-selected (FWT) and control (CLT) flock), were run together on pasture for a period from June to early December. At three times during this observation period (June, August and November) skin samples were taken from their midside flanks after local injection of bromodeoxyuridine (BrdU), to assess proliferation of bulb cells and several dimensional measurements of the follicle bulb and dermal papilla. FWT sheep had larger follicle dimensions than CLT sheep during winter and summer, with a greater number of proliferating bulb cells. Both flocks showed a seasonal change in follicle size, with a decline during winter, but the size of the dermal papilla was less affected than the germinative tissue area. Measurements of proliferation density (number of proliferating cells per area/volume of bulb tissue) suggest that changes in proliferation density do not contribute to flock differences in fleece production. However, during summer, FWT showed a 40% advantage over CLT sheep in hourly cell production based on data from three dimensional follicle bulb extrapolation. The different genotypes showed variations in width, as well as area of cortex and inner root sheath (IRS), measured across the top of the dermal papilla. The expression of these differences was further enhanced through seasonal influences, suggesting that there is an interaction between genetic/flock influences and seasonal influences on cell distribution to cortex and inner root sheath.

scholarly journals Studies In Depilation Ii. Structural Ohanges in the Wool Follicle During Bacterial Wool Loosening ("Sweating")

1968 ◽  
Vol 21 (2) ◽  
pp. 361 ◽  
Author(s):  
JR Yates
Keyword(s):  
Epidermal Cells ◽  
Wool Fibre ◽  
Fat Cells ◽  
Elastic Tissue ◽  
Structural Components ◽  
Outer Root Sheath ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Wool Follicle ◽  
Histological Staining

The changes in the various structural components of the wool follicle during the "sweating" process were followed by histological staining of sections prepared from the skin at appropriate intervals. Tissue breakdown starts in the lower part of the outer root sheath, progresses up the sheath, and ultimately involves the epidermis. The epidermis usually separates from the underlying dermis at a certain stage in the depilation process before the epidermal cells start to disintegrate. The gradual breakdown of the cells of the wool root bulb is an integral part of the wool� loosening process. The inner root sheath, the elastic tissue, and the fat cells are all broken down during depilation, but this is incidental to, and not the cause of, the loosening of the wool fibre. Sulphated mucopolysaccharides are gradually removed from the skin during depilation.

scholarly journals Theoretical Mechanism for Crimp

1981 ◽  
Vol 34 (2) ◽  
pp. 189 ◽  
Author(s):  
B N Nagorcka
Keyword(s):  
Mathematical Model ◽  
Cortical Cells ◽  
Rotational Movement ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Wool Follicle ◽  
Theoretical Mechanism

A mechanism for crimp in wool fibres is proposed in which the inner root sheath of the wool follicle and the fibre cuticle rotate around the fibre cortex in the region just above the follicle bulb. The rotational movement of the fibre cuticle is passed on to groups of microfibrils in the cortical cells of the fibre through a gearing action, which causes them to be twisted into helices or spirals with the result that the cortical cells tend to shorten. The fibre deforms while still in the follicle causing the position of the fibre cortex near the bulb to change. This changes the magnitude and direction of the rotational movement of the inner root sheath and cuticle. A mathematical model of the mechanism is developed and several crimp forms, produced by using the model, are compared to those commonly observed.

scholarly journals Trichohyalin, an intermediate filament-associated protein of the hair follicle.

1986 ◽  
Vol 102 (4) ◽  
pp. 1419-1429 ◽  
Author(s):  
J A Rothnagel ◽  
G E Rogers
Keyword(s):  
Molecular Weight ◽  
Hair Follicle ◽  
Polyclonal Antibodies ◽  
Side Chain ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Arginine Residues ◽  
Wool Follicle ◽  
Sheep Wool

A precursor protein associated with the formation of the citrulline-containing intermediate filaments of the hair follicle has been isolated and characterized. The protein, with a molecular weight of 190,000, was isolated from sheep wool follicles and purified until it yielded a single band on a SDS polyacrylamide gel. The Mr 190,000 protein has a high content of lysine and glutamic acid/glutamine residues and is rich in arginine residues, some of which, it is postulated, undergo a side chain conversion in situ into citrulline residues. Polyclonal antibodies were raised to the purified protein, and these cross-react with similar proteins from extracts of guinea pig and human follicles and rat vibrissae inner root sheaths. Tissue immunochemical methods have localized the Mr 190,000 protein to the trichohyalin granules of the developing inner root sheath of the wool follicle. We propose that the old term trichohyalin be retained to describe this Mr 190,000 protein. Immunoelectron microscopy has located the Mr 190,000 protein to the trichohyalin granules but not to the newly synthesized filaments. This technique has revealed that trichohyalin becomes associated with the filaments at later stages of development. These results indicate a possible matrix role for trichohyalin.

Patterns of epithelial expression of Fos protein suggest important role in the transition from viable to cornified cell during keratinization

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 253-258
Author(s):  
C. Fisher ◽  
M.R. Byers ◽  
M.J. Iadarola ◽  
E.A. Powers
Keyword(s):  
Cell Death ◽  
Cell Layer ◽  
Estradiol Benzoate ◽  
Binding Region ◽  
Ovariectomized Mice ◽  
Fos Protein ◽  
Root Sheath ◽  
Shift Analysis ◽  
Inner Root Sheath ◽  
Late Stages

An antibody directed against the DNA-binding region of c-fos was used to localize the distribution of cells positive for Fos protein in epithelial tissues. The antibody consistently bound to the nuclei of epithelial cells in the late stages of differentiation, just prior to cornification. The epidermis, palate, buccal mucosa, gingiva, tongue, forestomach and vagina in estrus all produced this type of labelling, suggesting a burst of expression immediately before cell death and cornification. The differentiating cells of the hair follicle, including the hair and inner root sheath, were also labelled. Non-keratinized tissues including junctional epithelium, embryonic epidermis and diestrus vaginal epithelium showed little or no Fos labelling. With the onset of keratinization at 18 days gestation or with induction of estrus in ovariectomized mice with estradiol benzoate, the epidermis and vagina expressed Fos protein in the manner typical for keratinized tissues. The Er/Er mutant epidermis, a tissue that is blocked in its ability to keratinize, overexpresses Fos with Fos-positive cells appearing in virtually every cell layer. Gel shift analysis demonstrates the presence of a functional AP-1 complex in epidermal extracts that is recognized by our antibody. Our data suggest that the expression of Fos is intricately related to epithelial cell differentiation, specifically in relation to the process of cornification and cell death.

Observations on the wool follicle abnormalities in Merino sheep exposed to prolonged wetting conducive to the development of fleece-rot

1977 ◽  
Vol 28 (6) ◽  
pp. 1095 ◽  
Author(s):  
T Nay ◽  
JE Watts
Keyword(s):  
Wool Fibre ◽  
Histopathological Changes ◽  
Merino Sheep ◽  
Fibre Breakage ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Vertical Distributions ◽  
Wool Follicle ◽  
Preliminary Study ◽  
Horizontal And Vertical Distributions

Groups of sheep found to be resistant and susceptible to fleece-rot following prolonged periods of natural and experimental rainfall were used in a preliminary study of the histopathological changes associated with the development of this condition. Wool follicle abnormalities affecting the growth of the wool fibre and inner root sheath were frequently observed. Weakened stretches of fibres, which appeared to result from impaired keratinization, were the sites of fibre breakage in the skin. Hypertrophic thickening and duplication of the inner root sheath occurred, and this material encased the proximal ends of broken fibres to form 'plugs'. The plugs grew vigorously in sheep that developed fleece-rot, apparently breaking the continuity of the skin as they emerged into the fleece. Fragments of plugs, broken wool fibres and exudate were present in fleece-rot bands along with cornified epithelial cells. Attempts to quantify the frequency of these abnormalities were complicated by marked variations in their horizontal and vertical distributions in the skin.

An Ultrastructural Study of the Membranes of Keratinizing Wool Follicle Cells

1972 ◽  
Vol 11 (1) ◽  
pp. 205-219
Author(s):  
D. F. G. ORWIN ◽  
R. W. THOMSON
Keyword(s):  
Hair Follicle ◽  
Ultrastructural Study ◽  
Plasma Membranes ◽  
Follicle Cells ◽  
Intercellular Spaces ◽  
Membrane Complex ◽  
Cytoplasmic Material ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Wool Follicle

Measurements of the widths of apposed plasma membranes and of the spaces between them were made at different stages of differentiation of keratinizing and hardening cells of the wool follicle. In contrast to findings in the hair follicle, no changes were detected for apposed cortex, cortex/fibre cuticle and fibre cuticle/fibre cuticle cells until keratinization had taken place. The trilaminar appearance of the plasma membranes was then lost and the intercellular material decreased in width. However, the inner root sheath cells developed a ‘membrane complex’ in enlarged intercellular spaces prior to hardening. Desmosomes are apparently retained in the hardened ‘membrane complexes’. A band of cytoplasmic material was also formed adjacent to the inner lamellae of the plasma membranes immediately before hardening of the cells. The presence of gap and tight junctions in differentiating cell lines of the wool follicle was noted.

scholarly journals A Polysaccharide-Containing Cell Coat on Keratinizing Cells of the Romney Wool Follicle

1970 ◽  
Vol 23 (3) ◽  
pp. 623 ◽  
Author(s):  
DFG Orwin
Keyword(s):  
Cell Growth ◽  
Cell Membrane ◽  
Cell Shape ◽  
Periodic Acid ◽  
Cellular Adhesion ◽  
Cell Coat ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Wool Follicle

The periodic acid-silver methenamine test revealed the presence of a polysaccharide- containing cell coat on the surfaces of keratinizing cells of the Romney wool follicle. This coat was present throughout the changes involving cellular adhesion, cell growth, and cell shape which occur before keratinization is complete. Once these changes were complete, the cell membrane, or regions close to it, and the cell coat of the cortex and the cortex cuticle cells became modified. Modifications of the cell membrane, or regions close to it, in the inner root sheath occurred on or just prior to hardening of these cells.

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