The mammary hair of Monodelphis domestica and homology of the mammary pilosebacous unit.

The unitary mammary gland is a synapomorphy of therian mammals and is thought to have evolved from the pilosebaceous organ in the mammalian stem lineage from which the lactogenic patch of monotremes is also derived. One of the key lines of evidence for the homology of the nipple and the lactogenic patch is that marsupials have retained a transient hair associated with developing mammary glands. However, these structures have not been documented since the early 20th-century drawings of Ernst Bresslau. In this study, we examine the developing mammary organs of Monodelphis domestica and document the presence of mammary hairs in 12-week-old females, as well as their absence after 18 weeks of age. Histochemical staining for cystine confirms the structures as keratinized hairs. Milk ducts of both juvenile and adult nipples show a division between KRT18+ luminal epithelium and KRT14+ ACTA2+ myoepithelium. These patterns match those in eutherians and suggest a conserved ductal morphology and mechanism of milk expulsion. Finally, PTHLH, a peptide hormone which promotes homeotic transformation of hairy skin into hairless nipples in the mouse, was detected in the Monodelphis milk duct during the mammary hair stage, suggesting that the mutual exclusivity of "hairless nipple" and "hair" organ identity is derived in eutherian mammals. These results reveal shared characteristics of the M. domestica nipple with both the eutherian nipple and the pilosebaceous organ, consistent with the evolutionary derivation of the mammary gland from an ancestral hair organ via developmental individualization of pilosebaceous and mammary identities.

Hair Coat of the Water Deer Hydropotes inermis (Cervidae, Artiodactyla), a New Species in the Russian Fauna.

The hair coat and hair microstructure of an adult male Hydropotes inermis from the Primorsky Krai of Russia were studied for the first time by light and scanning electron microscopy. Lack of abundant underfur, sparse hair, and a weak layering are characteristic of the species, which inhabits the temperate monsoon and tropical zones and does not need an efficient thermal protection. An alveolar and lattice medulla of the hair is similar to that of other deer, is well developed, and increases the heat-protective properties of the hair because seasonal and daily fluctuations in temperature and humidity can be significant. The cuticle pattern is similar to that of the deer tribes Alceini and Capreolini. The hair thickness and length are substantial on the back, sides, and thighs, and the coat thus provides reliable protection from mechanical damage when the water deer moves through thickets of bushes and grasses along riverbanks and swamps in its habitats. A knotty nature of hairs protects the skin from sharp outgrowths of aquatic and marsh plants.

Hundreds of body parts are named after hair: is anatomical terminology supercilious or simply super silly?

Relatively more-apparent body parts are often used to name relatively less-apparent body parts. To explore this etymological phenomenon, this report assesses anatomical terminology derived from some of the most apparent structures of the human body-hairs. Hair-related anatomical terminology involves varied etymons, roots, and derivatives: calvus "bald," cilia "eyelashes," glaber "hairless," pilus "hair," pubes (historically referring to the developing beard), pudendum "modesty" (referring to hair growth that covers genitalia), tempus "time" (referring to the location where hair commonly grays, thus showing a person's age), and tragus "goat" (referring to the tuft of hair that resembles the beard of a goat). Also including lanugo, vibrissae, hirci, flocculus, and cauda equina, a systematic review of Terminologia Anatomica and Terminologia Neuroanatomica revealed 285 unique non-duplicate hair-related terms. Several anatomical terms allude to particular age groups or sexes, but are used indiscriminately (e.g., tragus alludes to the older male ear, though may describe the fetal female ear). Likewise, human-centric anatomical terminology influences non-human anatomical terminology- a turtle has a "temporal bone" only because some humans develop gray hair on the sides of their heads as they age. Accordingly, etymological recursion is common: The human ear has a tragus, named after the goat, and the goat ear has a tragus, named after the human tragus, that was named after the goat. The use of Latin as the foundation of anatomical and medical terminology may appear seriously supercilious; however, it is often simply super silly. After all, hundreds of body parts are formally named after hair.

The Trotter collection: A review of Mildred Trotter's hair research and an update for studies of human variation.

OBJECTIVES: Mildred Trotter was an anatomist and physical anthropologist whose studies on hair morphology, growth, somatic distribution, and trait relationships to age and ethnogeographic population were foundational to the field of microscopical hair analysis. The collection of human hair samples she assembled for her research has been an underutilized resource for studies on human hair variation. We applied updated methods and reviewed Trotter's original data to reassess the relationship hair traits have to diverse population labels. METHODS: Hair form and pigmentation patterns were measured from a subset of the hair samples accumulated by Trotter and we compared our data to Trotter's original results. Variability in hair traits were tested within individuals, within populations, and among ethnogeographic groups. RESULTS: Measured hair cross-section dimensions and melanosome density and distribution revealed substantial variability within individuals and ethnogeographic populations. Hair traits were found to not be distinctly separable by ancestry but instead showed continuous variation across human populations. Trotter's measurements were precise and the dataset she compiled remains valid, though the conclusions should be reviewed in light of our current understanding of human variation. DISCUSSION: Our findings support moving away from categorical ancestry classifications and eliminating the use of outdated racial typologies in favor of more descriptive trait analysis. Detailed analysis of trait pattern distributions are presented that may be useful for future research on human variation. We point to the need for additional research on human variation and hair trait relationships with reference to known population affinity.

Human scalp hair as a thermoregulatory adaptation.

Humans are unique among mammals in having a functionally naked body with a hair-covered scalp. Scalp hair is exceptionally variable across populations within Homo sapiens. Neither the function of human scalp hair nor the consequences of variation in its morphology have been studied within an evolutionary framework. A thermoregulatory role for human scalp hair has been previously suggested. Here, we present experimental evidence on the potential evolutionary function of human scalp hair and variation in its morphology. Using a thermal manikin and human hair wigs at different wind speeds in a temperature and humidity-controlled environment, with and without simulated solar radiation, we collected data on the convective, radiative, and evaporative heat fluxes to and from the scalp in relation to properties of a range of hair morphologies, as well as a naked scalp. We find evidence for a significant reduction in solar radiation influx to the scalp in the presence of hair. Maximal evaporative heat loss potential from the scalp is reduced by the presence of hair, but the amount of sweat required on the scalp to balance the incoming solar heat (i.e., zero heat gain) is reduced in the presence of hair. Particularly, we find that hair that is more tightly curled offers increased protection against heat gain from solar radiation.

Reimagining Hair Science: A New Approach to Classify Curly Hair Phenotypes via New Quantitative Geometric and Structural Mechanical Parameters.

Hair is a natural polymeric composite primarily composed of tight macrobundles of keratin proteins, which are highly responsive to external stimuli, similarly to the hydrogels and other natural fibrous gel systems like collagen and fibrin.Hair and its appearance play a significant role in human society. As a highly complex biocomposite system, it has been traditionally challenging to characterize and thus develop personal care products. Over the last few decades, a significant societal paradigm shift occurred among those with curly hair, accepting the natural morphological shape of their curls and styling their hair according to its innate, distinct, and unique material properties, which has given rise to the development of new hair classification systems, beyond the traditional and highly limited race-based distinction (Caucasian, Mongolian, and African). L'Oréal developed a hair typing taxonomy based on quantitative geometric parameters among the four key patterns─straight, wavy, curly, and kinky, but it fails to capture the complex diversity of curly and kinky hair. Acclaimed celebrity hair stylist Andre Walker developed a classification system that is the existing gold standard for classifying curly and kinky hair, but it relies upon qualitative classification measures, making the system vague and ambiguous of phenotypic differences. The goal of this research is to use quantitative methods to identify new geometric parameters more representative of curly and kinky hair curl patterns, therefore providing more information on the kinds of personal care products that will resonate best with them and thus maximize desired appearance and health, and to correlate these new parameters with its mechanical properties. This was accomplished by identifying new geometric and mechanical parameters from several types of human hair samples.Geometric properties were measured using scanning electron microscopy (SEM), photogrammetry, and optical microscopy. Mechanical properties were measured under tensile extension using a texture analyzer (TA) and a dynamic mechanical analyzer (DMA), which bears similarity to the common act of brushing or combing. Both instruments measure force as a function of applied displacement, thus allowing the relationship between stress and applied stretch ratio to be measured as a hair strand uncurls and stretches to the point of fracture. From the resulting data, correlations were made between fiber geometry and mechanical performance. This data will be used to draw more conclusions on the contribution that fiber morphology has on hair fiber mechanics and will promote cultural inclusion among researchers and consumers possessing curly and kinky hair.

Recetario médico-farmacológicos para el cuidado y el embellecimiento del cabello: fuentes árabes medievales / [Medical-pharmacological recipes for hair care and beautification: medieval Arabic sources]

El cuidado y el embellecimiento del cabello forman parte de la tradición de todas las culturas y, a lo largo de la historia, los hombres y las mujeres se han preocupado por su aspecto, no solo desde el punto de vista estético sino también desde el punto de vista terapéutico. Un cabello sano indica una piel sana y, por lo tanto, un cuerpo sano. El trabajo que aquí presentamos recoge una colección de recetas de carácter médico-farmacológico destinadas al cuidado y el embellecimiento del cabello. Para ello, y partiendo de la Materia Médica de Dioscórides, obra de cabecera de la ciencia árabe, se han seleccionado una serie de fuentes árabes medievales de las que se han extraído dichas recetas. Los autores elegidos son: Al-Idrīsī, Abū l-Qāsim al-Zahrāwī, Abū l-ʿAlā’ Zuhr, Ibn Zuhr e Ibn al-Bayttār (AU)

En pos de la belleza. Cuidado de rostro y cabellos en el corpus textual hebreo de medicina / [In pursuit of beauty. Face and hair care in the Hebrew textual corpus of medicine]

Este trabajo presenta el resultado preliminar de una investigación en curso sobre tres géneros o tipologías textuales hebreas de (o con) contenido cosmético poco estudiados hasta ahora: recetarios, libros de medicina general y recetas sueltas. El análisis se ha basado en una muestra de textos concretos, con el fin de que sirvan como estudio de caso, en los que nos hemos centrado en las recetas y procedimientos dedicados a rostro y cabellos, por los que todos ellos revelan una preocupación notoria. Por un lado, se han examinado los diversos propósitos de las recetas, así como los ingredientes, técnicas y procedimientos. Por otro, hemos prestado atención a cómo se articulan el conocimiento y las técnicas cosméticas en distintos contextos médicos que no siempre tienen como objetivo aparente la salud femenina pero que se desarrollan en el marco de los discursos sobre la diferencia sexual y en la intersección de género, clase social y etnicidad. (AU)

Anatomical Landmarks of the Beard Region.

BACKGROUND: With recent advancements in hair restoration techniques, hair can be transplanted into nonscalp areas, such as the beard region, and the result looks natural. Although scalp zones and landmarks have been available for planning and designing the hairline, landmarks that will determine the beard lines are yet to be presented and made known for clinical practice. OBJECTIVE: This study aimed to determine and analyze the beard lines and anatomical boundaries of the beard area to provide a more natural restoration/reconstruction appearance. MATERIALS AND METHODS: The soft-tissue landmarks of the face that will enable physicians to create natural-looking beard lines were determined. Based on these important points, beard lines were analyzed with anthropometric methods by using the photographs of 32 male volunteers. RESULTS: The ideal upper and lower beard lines and the anatomical boundaries of the beard area were determined using these landmarks. CONCLUSION: These lines ensure that beard restoration/reconstruction provides a more natural appearance.

Classification Framework for Healthy Hairs and Alopecia Areata: A Machine Learning (ML) Approach.

Alopecia areata is defined as an autoimmune disorder that results in hair loss. The latest worldwide statistics have exhibited that alopecia areata has a prevalence of 1 in 1000 and has an incidence of 2%. Machine learning techniques have demonstrated potential in different areas of dermatology and may play a significant role in classifying alopecia areata for better prediction and diagnosis. We propose a framework pertaining to the classification of healthy hairs and alopecia areata. We used 200 images of healthy hairs from the Figaro1k dataset and 68 hair images of alopecia areata from the Dermnet dataset to undergo image preprocessing including enhancement and segmentation. This was followed by feature extraction including texture, shape, and color. Two classification techniques, i.e., support vector machine (SVM) and k-nearest neighbor (KNN), are then applied to train a machine learning model with 70% of the images. The remaining image set was used for the testing phase. With a 10-fold cross-validation, the reported accuracies of SVM and KNN are 91.4% and 88.9%, respectively. Paired sample T-test showed significant differences between the two accuracies with a p < 0.001. SVM generated higher accuracy (91.4%) as compared to KNN (88.9%). The findings of our study demonstrate potential for better prediction in the field of dermatology.

Development and qualification of a machine learning algorithm for automated hair counting.

OBJECTIVE: Determining the amount of hair on the scalp has always been an important metric of patient satisfaction for hair growth and hair retention technologies. While simple in concept, this measurement is a difficult, resource intensive task for the dermatologist and the research scientist. Specifically, counting and measuring hair in phototrichogram images is very time consuming and labour intensive. Due to cost, often only a fraction of available images is manually analysed. There is a need for an automated method that can significantly increase speed and throughput while reducing the cost of counting and measuring hair in phototrichogram images. METHODS: Recent advances in machine learning and deep convolutional neural networks (deep learning) have led to a revolution in the analysis of image, video, speech, text and other sensor data. Image diagnostics have seen remarkable improvements with completely automated methods outperforming both human experts and human-engineered analysis methods. Deep learning methods can also provide speed and cost benefits. To enable use of a deep learning, we created a data set of 288 manually annotated phototrichogram images with marked location and length of each hair (the training dataset). We designed a custom neural network architecture and custom image processing algorithms to best utilize the available training data and to maximize performance for hair counting and length measurement. The performance of the algorithm was qualified by comparing hair count and length measurements to an independent ground truth method, the semi-manual Canfield's Hair Metrix method. RESULTS: Leveraging deep neural networks, we have developed capability to apply machine learning to reduce the time needed to acquire data from phototrichograms of patients' scalp from months to seconds. Our algorithm enables fast and fully automated hair counting and length measurement. The algorithm shows high agreement with human manually assisted analysis (ground truth). CONCLUSIONS: We have trained and deployed an algorithm utilizing this technology and have demonstrated the reproducibility, accuracy and speed of this algorithm that, once deployed, requires little to no recurring cost or manual intervention for its operation. The method allows fast analysis of large number of images, reducing study cost and significantly reducing study analysis time.

Quantifying the contribution of Neanderthal introgression to the heritability of complex traits.

Eurasians have ~2% Neanderthal ancestry, but we lack a comprehensive understanding of the genome-wide influence of Neanderthal introgression on modern human diseases and traits. Here, we quantify the contribution of introgressed alleles to the heritability of more than 400 diverse traits. We show that genomic regions in which detectable Neanderthal ancestry remains are depleted of heritability for all traits considered, except those related to skin and hair. Introgressed variants themselves are also depleted for contributions to the heritability of most traits. However, introgressed variants shared across multiple Neanderthal populations are enriched for heritability and have consistent directions of effect on several traits with potential relevance to human adaptation to non-African environments, including hair and skin traits, autoimmunity, chronotype, bone density, lung capacity, and menopause age. Integrating our results, we propose a model in which selection against introgressed functional variation was the dominant trend (especially for cognitive traits); however, for a few traits, introgressed variants provided beneficial variation via uni-directional (e.g., lightening skin color) or bi-directional (e.g., modulating immune response) effects.

High-throughput phenotyping methods for quantifying hair fiber morphology.

Quantifying the continuous variation in human scalp hair morphology is of interest to anthropologists, geneticists, dermatologists and forensic scientists, but existing methods for studying hair form are time-consuming and not widely used. Here, we present a high-throughput sample preparation protocol for the imaging of both longitudinal (curvature) and cross-sectional scalp hair morphology. Additionally, we describe and validate a new Python package designed to process longitudinal and cross-sectional hair images, segment them, and provide measurements of interest. Lastly, we apply our methods to an admixed African-European sample (n = 140), demonstrating the benefit of quantifying hair morphology over classification, and providing evidence that the relationship between cross-sectional morphology and curvature may be an artefact of population stratification rather than a causal link.

Evaluation of morphological traits and physiological variables of several Chinese goat breeds and their crosses.

The current study was undertaken to evaluate some morphological traits of the goat breeds raised in Southwest China. The field experimentation and data collection were from 434 animals presenting seven breeds of the Dazu black goat (DBG; n = 203), Saanen milk goat (SMG; n = 50), Black Boer × Dazu black goat (BXC; n = 28), Hechuan white goat (HWG; n = 49), Inner Mongolia Cashmere goat (IMCG; n = 25), IMCG × DBG (F1; n = 57) and F1 × F1 (F2; n = 22). All studied animals were adult and selected to be at the same age (36.50 ± 0.75 months). After editing, more than 20 morphological and production traits like body condition score (BCS), testicle measurements, coat colour, fibre traits, skin colour, horn colour, horn shape, horn orientation, wattles, front hair, beard, ear shape, ear size, rump angle, hind leg angulation and physiological variables were analysed. BXC and DBG had dark coat colour, whilst SMG, HWG and IMCG had light colour, whilst F1 and F2 ranged from light to dark coat colour. Concerning BCS, the breeds BXC and DBG were characterized as fat goats, whilst SMG, HWG, F1 and F2 were average, whilst IMCG was thin. The maximum values for testis measurements were recorded for BXC, SMG and DBG. For fibre traits, IMCG, F1 and F2 were the most superior. BXC and DBG males have good fertility parameters. The highest values for rectal temperature, skin temperature and breath rate were recorded for SMG. These findings revealed the presence of a wide range of morphological differences among studied goat breeds. Such diversity in the performance of goat breeds raised in Southwest China is crucial to implement reliable selection strategies for breeding goats in this area.

Microscopical discrimination of human head hairs sharing a mitochondrial haplogroup.

In forensic analyses, determining the level of consensus among examiners for hair comparison conclusions and ancestry identifications is important for assessing the scientific validity of microscopical hair examinations. Here, we present data from an interlaboratory study on the accuracy of microscopical hair comparisons among a subset of experienced hair examiners currently analyzing hair in forensic laboratories across the United States. We examined how well microscopical analysis of hair can reliably be used to differentiate hair samples, many of which were macroscopically similar. Using cut hair samples, many sharing similar macroscopic and microscopic features, collected from individuals who share the same mitochondrial haplogroup as an indication of genetic relatedness, we tested multiple aspects that could impact hair comparisons. This research tested the extent to which morphological features related to ancestry and hair length influence conclusions. Microscopical hair examinations yielded accurate assessments of inclusion/exclusion relative to the reference samples among 85% of the pairwise comparisons. We found shorter hairs had reduced levels of accuracy and hairs from populations examiners were not familiar with may have impacted their ability to resolve features. The reliability of ancestry determinations is not yet clear, but we found indications that the existing categories are only somewhat related to current ethnic and genetic variation. Our results provide support for the continued utility of microscopical comparison of hairs within forensic laboratories and to advocate for a combined analytical approach using both microscopical analysis and mtDNA data on all forensic analyses of hair.

Wildlife forensics: A boon for species identification and conservation implications.

Wildlife trade and fraudulence in food, artefacts and cosmetic industries had raised serious concern in protection of the wild faunal diversity. Lack of proper tools and molecular based techniques for identification of wild species are some of the major constrains faced by the judiciary and law enforcement agencies while framing charges against poachers and illicit agitator. The emergence of wildlife forensics serves as a boon in solving long pending cases of wildlife crimes. Wildlife forensics have proven to be fast, accurate and reliable criminal investigation processes with comprehensive coverage and easy accessibility. It has also helped resolving taxonomic disputes, determining spatiotemporal genetic divergence, evolutionary history, origins and even endemism. Collaboration among inter-disciplinary fields has even led to engineered signature markers and phylogenetics for several species. Development in fields of genetics, molecular and evolutionary biology and other omics techniques have further contributed in accurate identification of species. Wildlife forensics, with the support of proper international mega database units for population reference, will be fundamental in wildlife investigations through its unlimited information sharing ability. The efficient conservation of species will, however, require a collaborative approach consisting of national policy makers, local stakeholders and implementation agencies in addition to experts from the scientific communities.

The curly coat phenotype of the Ural Rex feline breed is associated with a mutation in the lipase H gene.

Mutations in lipase H (LIPH) and lysophosphatidic acid receptor 6 (LPAR6), which are essential for the lysophosphatidic acid (LPA) signalling pathway, are associated with hypotrichosis and wooly hair in humans. Mutations in LPAR6 and keratin 71 (KRT71), result in unusual fur growth and hair structure in several cat breeds (Cornish Rex, Devon Rex and Selkirk Rex). Here, we performed target sequencing of the LIPH, LPAR6 and KRT71 genes in six cat breeds with specific hair-growth phenotypes. A LIPH genetic variant (LIPH:c.478_483del; LIPH:p.Ser160_Gly161del) was found in Ural Rex cats with curly coats from Russia, but was absent in all other cat breeds tested. In silico three-dimensional analysis of the LIPH mutant protein revealed a contraction of the α3-helix structure in the enzyme phospholipid binding site that may affect its activity.

Is ancestry, not natron, an explanation for fair haired children in Greco-Roman Egypt?

In an examination of three unwrapped mummified children from the Graeco-Roman Period of ancient Egypt there was an unexpected finding of fair hair. In the majority of unwrapped ancient Egyptian mummified bodies the hair was not fair but rather dark brown or black. To determine if exposure to natron during the mummification process was responsible for the fair hair color an experiment was carried out to partially replicate the environment in which bodies were desiccated. Fourteen samples of modern hair from various age groups, sex and ethnicity were subjected to synthetic natron for a period of 40 days to replicate the time taken to mummify a body. Macroscopic and microscopic examinations of samples were employed to ascertain any significant changes in hair color after treatment. Ancient wigs were studied for evidence of post mortem changes to hair color since construction over 2,000 years ago. Results of the study showed no significant lightening of hair color and in several samples the hair significantly darkened as the result of exposure to the natron. There was not any evidence that hair lightened as the result of natural post mortem changes and this was confirmed by the study of the natural hair wigs that had not changed color post mortem. This study concluded that the fair hair observed in the three child mummies was not the result of exposure to natron or post mortem changes but rather it was probably due to ancestry because of the presence of diverse genomes that were introduced into ancient Egypt during the Greco-Roman Period.

Autologous cell-based therapy for male and female pattern hair loss using dermal sheath cup cells: A randomized placebo-controlled double-blinded dose-finding clinical study.

BACKGROUND: Few effective treatments are available for male pattern hair loss (MPHL) or, especially, for female pattern hair loss (FPHL). Recently, cell-based therapies using autologous or allogeneic cells have been used clinically. OBJECTIVE: We examined the safety and efficacy of autologous cell-based therapy using dermal sheath cup (DSC) cells to treat MPHL and FPHL. METHODS: DSCs dissected from occipital hair follicles were cultured to manufacture DSC cells. Participants with MPHL or FPHL received single injections of 7.5 × 106, 1.5 × 106, or 3.0 × 105 DSC cells or a placebo in 4 randomized separate regions on the scalp, and hair densities and diameters were measured for 3, 6, 9, and 12 months. RESULTS: Fifty men and 15 women aged 33 to 64 years were injected with DSC cells. Total hair density and cumulative hair diameter at the 3.0 × 105 DSC cells injection site was significantly increased compared with the placebo after 6 and 9 months. Men and women showed similar improvements, and there were no serious adverse events. LIMITATIONS: No lower cell numbers were tested, and the positive effect was temporary until 9 months. CONCLUSION: The results suggest that cell therapy with autologous DSC cells may be useful as a new therapeutic method for treating MPHL and FPHL.