Transverse Microscopic Anatomy of the Human Scalp

Headington, John T.

doi:10.1001/archderm.1984.01650400031009

Cited by 358 publications

(84 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[8][9][10] Terminal-velluslike hair ratios were calculated from the follicular counts, and fibrous tracts were recorded as absent or present. Results are shown in the Table. The total number of hairs was identical in the control and laser-treated sites.…”

Section: Histological Findingsmentioning

confidence: 99%

“…A miniaturized terminal hair or secondary vellus hair is arbitrarily defined as having a cross-sectional hair shaft diameter of less than 30 mm. 9 Because the size of a hair depends on the size of the papilla and the hair bulb, 16 ruby laser pulses seem to miniaturize the papilla and the bulb either by direct photothermal injury or by injury to other structures of the follicle that control formation of the bulb with each anagen cycle.…”

mentioning

confidence: 99%

“…8,9,17 Male baldness is characterized by a proportional reduction in size of the papilla and the matrix. 16 Therefore, the terminal follicles are gradually transformed to velluslike follicles.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Permanent Hair Removal by Normal-Mode Ruby Laser

Dierickx¹,

Grossman²,

Farinelli³

et al. 1998

Arch Dermatol

237

179

View full text Add to dashboard Cite

Section: Histological Findingsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Permanent Hair Removal by Normal-Mode Ruby Laser

Dierickx¹,

Grossman²,

Farinelli³

et al. 1998

Arch Dermatol

237

179

View full text Add to dashboard Cite

“…The duration of such a cycle is variable but typically ranges from a few months to several years (5,6). Each follicle can undergo repeated cycles until it eventually dies or miniaturizes to give rise to a vellus hair (7,8); the vellus hair shaft is not pigmented and has a cross-sectional diameter much shorter than normal (9). Whether miniaturization (M) occurs progressively or abruptly is still unclear.…”

mentioning

confidence: 99%

Modeling the dynamics of human hair cycles by a follicular automaton

Halloy

Bernard

Loussouarn

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The hair follicle cycle successively goes through the anagen, catagen, telogen, and latency phases, which correspond, respectively, to hair growth, arrest, shedding, and absence before a new anagen phase is initiated. Experimental observations collected over a period of 14 years in a group of 10 male volunteers, alopecic and nonalopecic, allowed us to determine the characteristics of scalp hair follicle cycles. On the basis of these observations, we propose a follicular automaton model to simulate the dynamics of human hair cycles. The automaton model is defined by a set of rules that govern the stochastic transitions of each follicle between the successive states anagen, telogen, and latency, and the subsequent return to anagen. The transitions occur independently for each follicle, after time intervals given stochastically by a distribution characterized by a mean and a variance. The follicular automaton model accounts both for the dynamical transitions observed in a single follicle and for the behavior of an ensemble of independently cycling follicles. Thus, the model successfully reproduces the evolution of the fractions of follicle populations in each of the three phases, which fluctuate around steady-state or slowly drifting values. We apply the follicular automaton model to the study of spatial patterns of follicular growth that result from a spatially heterogeneous distribution of parameters such as the mean duration of anagen phase. When considering that follicles die or miniaturize after going through a critical number of successive cycles, the model can reproduce the evolution to hair patterns similar to well known types of diffuse or androgenetic alopecia.human scalp hair ͉ hair follicle cycles ͉ automaton model ͉ alopecia H uman hair represents an ensemble of some 10 5 hair follicles that continually evolve over the course of time. At any moment, a follicle is either growing (anagen or A phase) or ceasing to grow and involuting (catagen or C phase) but still on the scalp (telogen or T phase) before shedding and entering a new cycle. These successive phases constitute a follicular cycle (1-4). The duration of such a cycle is variable but typically ranges from a few months to several years (5, 6). Each follicle can undergo repeated cycles until it eventually dies or miniaturizes to give rise to a vellus hair (7,8); the vellus hair shaft is not pigmented and has a cross-sectional diameter much shorter than normal (9). Whether miniaturization (M) occurs progressively or abruptly is still unclear. If a large proportion of follicles die or miniaturize, alopecia-balding-ensues, with a severity that depends on the location of lost follicles (10) and on the amount of total hair that is irreversibly shed.The most comprehensive data on the human hair cycle were provided by a study carried out over a period of 14 years in a group of 10 normal and alopecic male volunteers (5, 6, 11). The data were collected by using the phototrichogram technique, which allowed determining the duration of A and T phases of each f...

show abstract

“…In human medicine, miniaturized follicles in male pattern alopecia are defined by the conversion of terminal hairs to vellus hairs 14) . A vellus hair has a cross-sectional (transverse) diameter of 0.03 mm or less, and its diameter does not exceed the thickness of the investing root sheath 11,32) .…”

Section: Discussionmentioning

confidence: 99%

Clinical and Histologic Description of Lykoi Cat Hair Coat and Skin

et al. 2016

View full text Add to dashboard Cite

Hair and skin abnormalities of domesticated animals are readily identified and are biomedical models for ectodermal dysplasias. The hair coat of the Lykoi cat, a new cat breed, is a dramatic phenotype and has not been clinically or histologically described. Dermatoscopic examination was performed and skin biopsies were collected from seven Lykoi cats and seven dermatologically normal domestic shorthair (DSH) cats. All skin structures were examined on longitudinal and transverse sections. Immunohistochemistry for CD3 and Cytokeratin 8/18 was performed for comparison with DSH cats. Dermatoscopic images were compared. Lykoi had a significant reduction in average numbers of follicles per hair follicle group as compared to DSH cats, 14.7 ± 2.9 and 23.4 ± 5.4, respectively. Median (range) numbers of hairs per hair follicle group were 1.3 (0.4-5.7) and 18.8 (10.6-26.6), respectively. Mean (± SD) hair follicle depth was 0.95 mm ± 0.15 and 1.14 mm ± 0.21 for Lykoi and DSH cats, respectively. Mean (± SD) primary hair shaft diameters were 39 µm ± 0.029 and 47 µm ± 0.011 for Lykoi and DSH cats, respectively. Mean (± SD) total sebaceous gland area per hair follicle group was 19,937.7 pixels 2 ± 10,254.9 and 9,833.7 pixels 2 ± 5,784.5 for Lykoi and DSH cats, respectively. Unlike DSH, Lykoi had mild to severe perifollicular to mural lymphocytic infiltration in 77% of observed hair follicle groups, and follicles were often miniaturized, dilated, and dysplastic. The Lykoi has a unique feline phenotype that may serve as a novel dermatological biomedical model.

show abstract

Transverse Microscopic Anatomy of the Human Scalp

Cited by 358 publications

References 2 publications

Permanent Hair Removal by Normal-Mode Ruby Laser

Permanent Hair Removal by Normal-Mode Ruby Laser

Modeling the dynamics of human hair cycles by a follicular automaton

Clinical and Histologic Description of Lykoi Cat Hair Coat and Skin

Contact Info

Product

Resources

About