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The purpose of the present study was to elucidate why keratinocytes of the outer root sheath (ORS) do not keratinize in situ. Two possibilities were considered--inhibition of keratinization is caused by contact of ORS with inner root sheath (IRS) or insufficient supply of keratinization promoting factors from the surrounding tissues to the ORS. In...
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The hair follicle consists of several distinctive epidermal cell layers. The hair root, which undergoes keratinization, is surrounded by two sheaths: the inner root sheath (IRS) and the outer root sheath (ORS). The ORS is continuous with the basal layer of the epidermis. Its cells do not keratinize in situ, unlike IRS. We have previously demonstrat...
Citations
... Indeed, the signal was detected in the inner and outer root sheaths of the hair follicles. The latter is in continuity with the basal layer of the epidermis and is generally rooted in the dermis, which explains the detection of the nanobody in this skin layer [50][51][52]. ...
Iontophoresis enables the non-invasive transdermal delivery of moderately-sized proteins and the needle-free cutaneous delivery of antibodies. However, simple descriptors of protein characteristics cannot accurately predict the feasibility of iontophoretic transport. This study investigated the cathodal and anodal iontophoretic transport of the negatively charged M7D12H nanobody and a series of negatively charged variants with single amino acid substitutions. Surprisingly, M7D12H and its variants were only delivered transdermally by anodal iontophoresis. In contrast, transdermal permeation after cathodal iontophoresis and passive diffusion was <LOQ. The anodal iontophoretic delivery of these negatively charged proteins was achieved because electroosmosis was the dominant electrotransport mechanism. Cutaneous deposition after the anodal iontophoresis of M7D12HWT (wild type), and the R54E and K65E variants, was statistically superior to that after cathodal iontophoresis (6.07 ± 2.11, 9.22 ± 0.80, and 14.45 ± 3.45 μg/cm2, versus 1.12 ± 0.30, 0.72 ± 0.27, and 0.46 ± 0.07 µg/cm2, respectively). This was not the case for S102E, where cutaneous deposition after anodal and cathodal iontophoresis was 11.89 ± 0.87 and 8.33 ± 2.62 µg/cm2, respectively; thus, a single amino acid substitution appeared to be sufficient to impact the iontophoretic transport of a 17.5 kDa protein. Visualization studies using immunofluorescent labeling showed that skin transport of M7D12HWT was achieved via the intercellular and follicular routes.
... Earlier we have shown that extraction resulted in its partial peeling from the inner root sheet [2]. In contrast to inner root sheet, the ORS cells are not keratinized and maintain mitochondrial activity [11] and this fact explains the proportionality between ATP content in HF and their length. Similarly, IL-10 content directly correlated with the length which could indicate its synthesis along the full length of ORS, which can be explained by its participation in providing immune privilege. ...
The concentrations of ATP, IL-6, and IL-10 were measured in extracts of plucked hair follicles from healthy volunteers (normal values) and patients with androgenetic alopecia and then, ATP, IL-6, and IL-10 content was calculated for each follicle. The resulting values were directly proportional to hair follicle length, except for IL-6. The concentration of extracted ATP correlated with lactate dehydrogenase activity indicating cell damage. In patients with androgenetic alopecia, IL-10 content exceeded the normal values in follicles with a length <1 mm and ATP content surpassed the normal in follicles >2 mm long. The content of IL-6 and IL-10 measured by ELISA was comparable with results of mRNA expression assayed by RT-PCR, which attested to moderate level of gene expression. The content of ATP and IL- 10, but not IL-6 depended on the length of plucked hair follicle and on pathogenetic factors affecting hair growth.
... The ORS forms the outermost epithelial layer of the hair follicle and represents a direct continuation of the basal layer of the epidermis. EGF was previously demonstrated to promote keratinization of ORS cells [21], and it induces epidermal differentiation at the expense of hair follicle fate [22]. Thus, high concentrations of EGF may promote differentiation of ORS cells, rather than proliferation. ...
Background/aims:
To investigate the effect and molecular mechanism of EGF on the growth and migration of hair follicle outer root sheath (ORS) cells.
Methods:
Intact anagen hair follicles were isolated from mink skin and cultured with EGF in vitro to measure ORS daily growth. Meanwhile, purified primary ORS cells were treated or transfected with EGF, and their proliferation and migration were assessed by MTT assay and transwell assay, respectively. The signaling pathway downstream of EGF was characterized by using the Wnt/β-catenin signaling inhibitor, XAV-939.
Results:
EGF of 2-20 ng/ml, not higher or lower, promoted the growth of follicular ORS in vitro. EGF treatment or overexpression promoted the proliferation and migration of ORS cells. Moreover, EGF stimulation induced nuclear translocation of β-catenin, and upregulated the expression of Wnt10b, β-catenin, EGF receptor and SOX9. Inhibition of Wnt/β-catenin signaling by XAV-939 significantly reduced the basal and EGF-enhanced proliferation and migration of ORS cells. In addition, a number of follicle-regulatory genes, such as Survivin, Msx2 and SGK3, were upregulated by EGF in the ORS cells, which was also inhibited by XAV-939.
Conclusion:
EGF promotes the proliferation and migration of ORS cells and modulates the expression of several follicle-regulatory genes via Wnt/β-catenin signaling.
... Hair bulb melanocytes were situated in the basal region of the hair matrix, resting on a basement membrane which separates it from the dermal papilla, as in a general description of the mouse by Boissy [8]. According to Niderla-Bielinska et al. [22], mesenchymal cells of the dermal papilla and dermal fibroblasts secrete regulatory factors that control the proliferation and differentiation of hair follicles. Midway up the dermal papilla undifferentiated hair matrix cells start to form 6 concentric layers from where they rise in the follicle to undergo their individual fates [21]. ...
... Instead, the inner root sheath ends at the duct of the sebaceous gland, from where it joins the stratum corneum [20,25]. At this position, both the inner root sheath and stratum corneum are shed into the follicle lumen as the hair shaft exits through the skin surface [22][23][24] which happened to be the same in the juvenile four-striped mouse skin. Separating the inner and outer root sheath is a monolayer of flattened cells known as the companion layer [20,26,27] and identified in the juvenile four-striped mouse hair follicle. ...
... Separating the inner and outer root sheath is a monolayer of flattened cells known as the companion layer [20,26,27] and identified in the juvenile four-striped mouse hair follicle. In our findings, the companion layer was associated with the Henle layer instead of the outer root sheath [20,22,27]. ...
The four-striped mouse has a grey to brown coloured coat with four characteristic dark stripes interspersed with three lighter stripes running along its back. The histological differences in the skin of the juvenile and adult mouse were investigated by Haematoxylin and Eosin and Masson Trichrome staining, while melanocytes in the skin were studied through melanin-specific Ferro-ferricyanide staining. The ultrastructure of the juvenile skin, hair follicles, and melanocytes was also explored. In both the juvenile and adult four-striped mouse, pigment-containing cells were observed in the dermis and were homogeneously dispersed throughout this layer. Apart from these cells, the histology of the skin of the adult four-striped mouse was similar to normal mammalian skin. In the juvenile four-striped mouse, abundant hair follicles of varying sizes were observed in the dermis and hypodermis, while hair follicles of similar size were only present in the dermis of adult four-striped mouse. Ultrastructural analysis of juvenile hair follicles revealed that the arrangement and differentiation of cellular layers were typical of a mammal. This study therefore provides unique transition pattern in the four-striped mouse skin morphology different from the textbook description of the normal mammalian skin.
... Birbeck (Birbeck and Mercer, 1957a) has indicated that the intracellular product was trichohyaline, and that trichohyaline was certainly a precursor of the fibrous component of the sheath. Justyna et al. (2009) has reported that cell keratinization begun in IRS in the He layer. The first signal of keratinization is the appearance of trichohyalin granules in keratinocytes (Birbeck and Mercer, 1957a;Morioka, 2005). ...
This experiment conducted to identify a periodic change of ultrastructures of secondary follicle characteristics during a whole year, reveal the molecule regulation of growth of cashmere. A total of 10 cashmere goats of 1-year old were studied. The paraffin section and ultrathin slices of skin were made each month in a whole year, observed, photographed, and analyzed under light microscope and transmission electron microscope after stained. Following the development of down fiber, the ultrastructures of secondary follicle of Hexi cashmere goat showed a periodic change within a year. There were five different periods during a down fiber cycle. It was observed that the stage of telogen, proanagen, anagen, procatagen, and catagen was in January and February, March and April, May to August, September and October, and November and December, respectively. The key change observed in secondary follicle under transmission electron microscope was inner root sheath. This study illustrated the five different stage of secondary follicle of Hexi Cashmere goat within a whole growth cycle, and has provided more detailed information about the research field of Hexi cashmere goat. Choosing the suitable time to harvest the cashmere may get the profit maximization.
Calcium (Ca+2) is the most abundant major mineral in the human body and accounts for 1–2% of adult human body weight [1]. No less than 99% of Ca+2 is found in bones and teeth where it supports their structure and function, while 1% is found in plasma and soft tissues. Despite the large amount of Ca+2 in the human body, intra- and extracellular Ca+2 levels are very tightly regulated in order to exert cellular functions efficiently [2]. This balance is regulated by the actions of parathyroid hormone (PTH), that in combination with Vit D, regulate Ca+2 homeostasis.
The pilosebaceous unit is a complex mini-organ consisting of three anatomic components: hair follicle, sebaceous gland, and arrector pili muscle. The proportions of these components vary among the different types of hair follicles. In this chapter, some interesting anatomical details of this impressively complex organ will be presented.
The inner root sheath (IRS) sustains and addresses the hair shaft outside the follicle. Ultrastructural analysis of immunolabeling for beta-catenin, plakophilin-1, desmoglein-4 and keratin-17 in human hairs has indicated that adherens junctions and desmosomes initially connect cells in mature IRS and the companion layer. Beta-catenin immunolabeling for adherens junctions is only seen in sparse regions of differentiating Huxley cells, Flugelzellen cells and Henle cells, but disappears in cornified cells of the IRS. Desmoglein-4 and plakophilin-1 immunolabeling are observed in differentiating and cornified desmosomes of the Huxley and Henle layers and in the membrane complex joining these cells. Desmoglein-4 and plakophilin-1 are more frequently immunolocalized in the intracellular side of the junctions, but some labeling is also present in the delta-layer of the membrane complex. The labeling indicates a prevalent intracellular redistribution of desmoglein-4 and plakophilin-1 when the final cornification of the IRS occurs. Intense keratin-17 immunolabeling is observed in tonofilaments of the companion layer joining the plakophilin-1 rich desmosomes of the Henle layer. This suggests that this elastic type of keratin is present at desmosome junctions during the movements of the companion layer along the slippage plane of the hair shaft.
The hair follicle consists of several distinctive epidermal cell layers. The hair root, which undergoes keratinization, is surrounded by two sheaths: the inner root sheath (IRS) and the outer root sheath (ORS). The ORS is continuous with the basal layer of the epidermis. Its cells do not keratinize in situ, unlike IRS. We have previously demonstrated that keratinization of the ORS was prevented by contact with the IRS in hair follicle mid-segments (i.e. fragments dissected from skin at the level above the hair bulb and below the opening of the sebaceous gland duct) cultured on agarose layer. The purpose of this study was to determine whether the same applies to the hair bulb. After isolation, intact bulbs or hair bulb-derived cells were incubated in suspension in a low or high calcium medium. The level of mRNA for differentiation markers: involucrin, filaggrin, keratinocyte differentiation associated protein and trichohyalin, was studied by RealTime PCR. We observed increased Ca(2+) upregulated expression of involucrin, filaggrin, trichohyalin and Kdap in cultures of bulb-derived cells, but in hair bulbs downregulation of involucrin and trichohyalin was observed. We concluded that the inner root sheath exerts an inhibitory effect on the expression of involucrin and trichohyalin already in the hair bulbs. The observation that downregulation of involucrin expression under Ca(2+) influence occurs both in hair bulb and midsegments could simplify future experiments, since their separation does not seem to be necessary.
