scholarly journals THE ELECTRON MICROSCOPY OF THE HUMAN HAIR FOLLICLE

1957 ◽  
Vol 3 (2) ◽  
pp. 223-230 ◽  
Author(s):  
M. S. C. Birbeck ◽  
E. H. Mercer
Keyword(s):  
Hair Follicle ◽  
Cross Sections ◽  
Plasma Membranes ◽  
Membrane Complex ◽  
Outer Sheath ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Cell Layers ◽  
Adhesive Contacts ◽  
Similar Complex

1. The three cylinders of cells, each one cell thick, which together constitute the inner root sheath, arise from the peripheral portions of the undifferentiated matrix. These cells, like the hair cuticle, are stabilised by the spread of adhesive contacts between their plasma membranes which occurs in the mid-bulb and upper bulb of the hair follicle. 2. The characteristic intracellular product of all three cell layers is trichohyaline. This substance is formed in the first place as amorphous droplets which subsequently transform into a birefringent form. 3. This transformation, involving the formation of a birefringent product from an amorphous precursor, is in contrast to the formation in the cortex of keratin which originates in a fibrous form. 4. Trichohyaline appears first and transforms first in the cells of Henle which are nearest the outer sheath and the dermal supply vessels. This transformation occurs at the level of the neck of the follicle. Synthesis and transformation in the cells of Huxley and the sheath cuticle lag behind the similar events in the cells of Henle. The transformation does not begin until the lower prekeratinous zone in the Huxley and cuticle cells. 5. The amorpous-fibrous transformation occurs rapidly cell by cell and involves the conversion of all the trichohyaline droplets. In longitudinal sections the birefringent modification can be seen extending from the droplets in both directions parallel to the axis of the hair. In cross-sections the images of the transformed material are difficult to interpret. They may be seen as sections of corrugated sheets (∼100 A thick) or condensed fibrils ∼100 A in width. 6. At the same time that the trichohyaline transforms, the spacing between the cell membranes increases and a dark deposit appears centrally between them. This membrane complex, and the similar complex of the hair cuticle cells described in Part 2, may be specialised formations whose purpose is to hold the hardened cells together.

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 THE ELECTRON MICROSCOPY OF THE HUMAN HAIR FOLLICLE

1957 ◽  
Vol 3 (2) ◽  
pp. 215-222 ◽  
Author(s):  
M. S. C. Birbeck ◽  
E. H. Mercer
Keyword(s):  
Electron Microscopy ◽  
Hair Follicle ◽  
Late Stage ◽  
Final Stage ◽  
Human Hair ◽  
Plasma Membranes ◽  
Human Hair Follicle ◽  
Laminated Structure ◽  
Root Sheath ◽  
Inner Root Sheath

1. During the early differentiation of the cuticle the cell membranes smooth out and the cells become closely attached over most of their surface. The change seems to be due to a layer of cement which forms between them. The plasma membranes also increase in density. 2. The decreased membrane activity of the cuticle cells may prevent a phagocytosis of the melanocyte processes and thus account for the non-pigmentation of the cuticle. 3. The flattening and imbrication of the cuticle may possibly be explained by a zipper-like spread of cell contacts. 4. Keratinisation of the cuticle occurs at a late stage in its development; the keratin formed is an amorphous type, similar to the γ-fraction of the cortex which is produced at a similar level. 5. Keratinisation is accompanied by the formation of complex intercellular layers similar to structures observed in the inner root sheath (see Part 3). 6. In the final stage of keratinisation the remaining cytoplasm condenses with the result that the cell is divided into a laminated structure with an outer keratinised layer and an inner layer, which is insoluble in keratinolytic solvents.

A Selectable Biomarker in Hair Follicle Cycles – Cathepsins: A Preliminary Study in Murine

2021 ◽  
pp. 1-7
Author(s):  
Jingzhu Bai ◽  
Zijian Gong ◽  
Qingfang Xu ◽  
Haiyan Chen ◽  
Qiaoping Chen ◽  
...  
Keyword(s):  
Hair Follicle ◽  
Hair Cycle ◽  
Biological Factors ◽  
Outer Root Sheath ◽  
Physiological Processes ◽  
Intervention Measures ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Preliminary Study ◽  
Paraffin Method

<b><i>Background/Objective:</i></b> Hair cycle is regulated by many biological factors. Cathepsins are involved in various physiological processes in human skin. Here, we investigated the cathepsin expression and distribution changes in follicular growth cycles for better understanding the hair cycles and to explore new intervention measures. <b><i>Methods:</i></b> The 24 mice (C57BL/6, female, 7-week old) were selected and removed the back hair via rosin/paraffin method. At Day 8, Day 20, and Day 25, biopsy on post-plucking area was done. Immunohistochemical staining, Western blot, and Q-PCR were used to test the cathepsin B/D/L/E. <b><i>Results:</i></b> In anagen, cathepsins (B, D, L, and E) were distributed in the hair follicle matrix, inner hair root sheath, and hair. In catagen, cathepsins were mainly observed in un-apoptosis inner root sheath and outer root sheath. Expression of cathepsins B-mRNA and L-mRNA was decreased from anagen and catagen to telogen. Cathepsin D-mRNA was increased in catagen and then decreased in telogen. Cathepsin E-mRNA was decreased in catagen and slightly increased in telogen. <b><i>Conclusions:</i></b> The distribution and expression of cathepsins B, D, L, and E in hair follicle changed with hair growth process which indicated that cathepsins might act as selectable biomarkers of hair cycle in different stages.

Synthesis of porcine pCLCA2 protein during late differentiation of keratinocytes of epidermis and hair follicle inner root sheath

2012 ◽  
Vol 350 (3) ◽  
pp. 445-453 ◽  
Author(s):  
Stephanie Plog ◽  
Lars Mundhenk ◽  
Lutz Langbein ◽  
Achim D. Gruber
Keyword(s):  
Hair Follicle ◽  
Root Sheath ◽  
Inner Root Sheath

scholarly journals 889 Trpv3 gain-of-function mutation impairs differentiation of hair follicle inner root sheath

2019 ◽  
Vol 139 (5) ◽  
pp. S154
Author(s):  
Z. Song ◽  
X. Chen ◽  
Q. Zhao ◽  
Z. Lin ◽  
S. Yang ◽  
...  
Keyword(s):  
Hair Follicle ◽  
Gain Of Function ◽  
Root Sheath ◽  
Inner Root Sheath

scholarly journals Defining BMP functions in the hair follicle by conditional ablation of BMP receptor IA

2003 ◽  
Vol 163 (3) ◽  
pp. 609-623 ◽  
Author(s):  
Krzysztof Kobielak ◽  
H. Amalia Pasolli ◽  
Laura Alonso ◽  
Lisa Polak ◽  
Elaine Fuchs
Keyword(s):  
Hair Follicle ◽  
Progenitor Cells ◽  
Gene Targeting ◽  
Transcriptional Activation ◽  
Hair Shaft ◽  
Bmp Receptor ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Conditional Gene Targeting ◽  
Sequential Inhibition

Using conditional gene targeting in mice, we show that BMP receptor IA is essential for the differentiation of progenitor cells of the inner root sheath and hair shaft. Without BMPRIA activation, GATA-3 is down-regulated and its regulated control of IRS differentiation is compromised. In contrast, Lef1 is up-regulated, but its regulated control of hair differentiation is still blocked, and BMPRIA-null follicles fail to activate Lef1/β-catenin–regulated genes, including keratin genes. Wnt-mediated transcriptional activation can be restored by transfecting BMPRIA-null keratinocytes with a constitutively activated β-catenin. This places the block downstream from Lef1 expression but upstream from β-catenin stabilization. Because mice lacking the BMP inhibitor Noggin fail to express Lef1, our findings support a model, whereby a sequential inhibition and then activation of BMPRIA is necessary to define a band of hair progenitor cells, which possess enough Lef1 and stabilized β-catenin to activate the hair specific keratin genes and generate the hair shaft.

scholarly journals A Novel Epithelial Keratin, hK6irs1, is Expressed Differentially in All Layers of the Inner Root Sheath, Including Specialized Huxley Cells (Flügelzellen) of the Human Hair Follicle

2002 ◽  
Vol 118 (5) ◽  
pp. 789-799 ◽  
Author(s):  
Lutz Langbein ◽  
Silke Praetzel ◽  
Michael A. Rogers ◽  
Noriaki Aoki ◽  
Hermelita Winter ◽  
...  
Keyword(s):  
Hair Follicle ◽  
Human Hair ◽  
Human Hair Follicle ◽  
Root Sheath ◽  
Inner Root Sheath

scholarly journals Characteristic Localization of Neuronatin in Rat Testis, Hair Follicle, Tongue, and Pancreas

2019 ◽  
Vol 67 (7) ◽  
pp. 495-509
Author(s):  
Naoko Kanno ◽  
Saishu Yoshida ◽  
Takako Kato ◽  
Yukio Kato
Keyword(s):  
Hair Follicle ◽  
Intracellular Localization ◽  
Taste Receptor ◽  
Hair Follicles ◽  
Rat Tissues ◽  
Basal Cells ◽  
Fungiform Papilla ◽  
Differentiated Cells ◽  
Root Sheath ◽  
Inner Root Sheath

Neuronatin ( Nnat) is expressed in the pituitary, pancreas, and other tissues; however, the function of NNAT is still unclear. Recent studies have demonstrated that NNAT is localized in the sex-determining region Y-box 2-positive stem/progenitor cells in the developing rat pituitary primordium and is downregulated during differentiation into mature hormone-producing cells. Moreover, NNAT is widely localized in subcellular organelles, excluding the Golgi. Here, we further evaluated NNAT-positive cells and intracellular localization in embryonic and postnatal rat tissues such as the pancreas, tongue, whisker hair follicle, and testis. Immunohistochemistry revealed that NNAT was localized in undifferentiated cells (i.e., epithelial basal cells and basement cells in the papillae of the tongue and round and elongated spermatids of the testis) as well as in differentiated cells (insulin-positive cells and exocrine cells of the pancreas, taste receptor cells of the fungiform papilla, the inner root sheath of whisker hair follicles, and spermatozoa). In addition, NNAT exhibited novel intracellular localization in acrosomes in the spermatozoa. Because the endoplasmic reticulum (ER) is excluded from spermatozoa and sarco/ER Ca2+-ATPase isoform 2 (SERCA2) is absent from the inner root sheath, these findings suggested that NNAT localization in the ER and its interaction with SERCA2 are cell- or tissue-specific properties.

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