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.

Communication compartments in hair follicles and their implication in differentiative control

Development ◽  
1992 ◽  
Vol 114 (2) ◽  
pp. 389-393 ◽  
Author(s):  
E. Kam ◽  
M.B. Hodgins
Keyword(s):  
Lucifer Yellow ◽  
Early Stage ◽  
Dermal Papilla ◽  
Hair Follicles ◽  
Hair Dye ◽  
Hair Bulb ◽  
Ultrastructural Studies ◽  
Junctional Communication ◽  
Root Sheath ◽  
Inner Root Sheath

Observations on hair follicles presented in this paper show that boundaries to junctional communication are formed between groups of cells following different pathways of differentiation. The patterns of junctional communication in the bulbs of rat vibrissa follicles and human hair follicles were studied by microinjection of the fluorescent tracer dye Lucifer Yellow CH. Dye spread was extensive between undifferentiated cells of the hair bulb matrix but communication boundaries were found between groups of morphologically distinct cells. For example, boundaries to dye spread were observed between undifferentiated matrix cells and cells in the early stage of differentiation into the inner root sheath, between Huxley's and Henle's layers in the early inner root sheath and between cells of the cuticle and cortex of the hair. Dye did not spread between epithelial cells of the hair bulb and mesenchymal cells of the connective tissue sheath or dermal papilla. The patterns of dye spread became more complex (increased boundary formation and subcompartmentation) as differentiation progressed in higher regions of the hair bulb. The observed communication can be related to previous ultrastructural studies by others on the distribution of gap junctions in the wool follicle. These results show that junctional communication, with its consequent intercellular spread of small ions and molecules, is associated with uniformity of expression and behaviour within cell populations and that interruption of communication through the formation of boundaries and communication compartments is temporally and spatially related to the production of subpopulations of cells committed to the expression of different phenotypes.

scholarly journals Wnt10b promotes hair follicles growth and dermal papilla cells proliferation via Wnt/β-Catenin signaling pathway in Rex rabbits

2020 ◽  
Vol 40 (2) ◽  
Author(s):  
Zhenyu Wu ◽  
Yanli Zhu ◽  
Hongli Liu ◽  
Gongyan Liu ◽  
Fuchang Li
Keyword(s):  
Cell Cycle ◽  
Signaling Pathway ◽  
Cell Cycle Progression ◽  
Dermal Papilla ◽  
Hair Shaft ◽  
Hair Follicles ◽  
Dermal Papilla Cells ◽  
Root Sheath ◽  
Inner Root Sheath

Abstract Wnt signaling plays an important role in the growth and development of hair follicles (HFs). Among the signaling molecules, Wnt10b was shown to promote the differentiation of primary skin epithelial cells toward the hair shaft and inner root sheath of the HF cells in mice in vitro. Whisker HFs were isolated from Rex rabbits and cultured in vitro to measure hair shaft growth. Meanwhile, dermal papilla cells (DPCs) were isolated and cultured in vitro. Treatment with AdWnt10b or the Wnt/β-Catenin Pathway inhibitor, XAV939, assessed the DPCs proliferation by CCK-8 assay. And the cell cycle was also analyzed by flow cytometry. We found that Wnt10b could promote elongation of the hair shaft, whereas XAV-939 treatment could eliminated this phenomenon. AdWnt10b treatment promoted the proliferation and induced G1/S transition of DPCs. AdWnt10b stimulation up-regulated β-Catenin protein in DPCs. Inhibition of Wnt/β-Catenin signaling by XAV-939 could decreased the basal and Wnt10b-enhanced proliferation of DPCs. And could also suppress the cell cycle progression in DPCs. In summary, our study demonstrates that Wnt10b could promote HFs growth and proliferation of DPCs via the Wnt/β-Catenin signaling pathway in Rex rabbits.

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.

scholarly journals Regulation of prolactin receptor expression in ovine skin in relation to circulating prolactin and wool follicle growth status

2002 ◽  
Vol 172 (3) ◽  
pp. 605-614 ◽  
Author(s):  
AJ Nixon ◽  
CA Ford ◽  
JE Wildermoth ◽  
AJ Craven ◽  
MG Ashby ◽  
...  
Keyword(s):  
In Situ Hybridisation ◽  
Dermal Papilla ◽  
Hair Follicles ◽  
Receptor Expression ◽  
Ribonuclease Protection Assay ◽  
Plasma Prolactin ◽  
Follicle Growth ◽  
Outer Root Sheath ◽  
Root Sheath ◽  
Wool Follicle

Seasonal patterns of hair growth are governed, at least in part, by levels of prolactin in circulation, and although receptors for prolactin (PRLR) have been demonstrated in hair follicles, little is known of their regulation in relation to follicular cycles. In this study, a photoperiod-generated increase in prolactin was used to induce a wool follicle cycle during which changes in PRLR expression in sheep skin were determined by ribonuclease protection assay and in situ hybridisation. mRNA for prolactin and both isoforms of PRLR were also detected in skin by reverse transcription and polymerase chain reaction. As circulating prolactin began to rise from low levels, PRLR mRNA in the skin initially fell. These changes immediately preceded the catagen (regressive) phase of the hair cycle. Further increase in prolactin resulted in up-regulation of PRLR during telogen (dormancy), particularly in the epithelial hair germ, to reach a peak during proanagen (reactivation). In anagen (when follicle growth was fully re-established), PRLR mRNA returned to levels similar to those observed before the induced cycle. Hence, this longer term rise and fall of PRLR expression followed that of plasma prolactin concentration with a lag of 12-14 days. PRLR mRNA was most abundant in the dermal papilla, outer root sheath, hair germ, skin glands and epidermis. Location of PRLR in the dermal papilla and outer root sheath indicates action of prolactin on the growth-controlling centres within wool follicles. These cycle-related patterns of PRLR expression suggest dynamic regulation of PRLR by prolactin, thereby modulating hormonal responsiveness of seasonally growing hair follicles.

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.

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.

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.

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