Hair directional slope is secondary to the plane of stretch exerted on the skin by the growth of underlying tissues during the period of down-growth of the hair follicles at around 10-12 weeks gestation. The posterior parietal hair whorl is interpreted as the focal point from which the growth stretch is exerted by the dome-like out-growth of the brain during the time of hair follicle development. Malformations that antedate hair follicle development, such as encephalocele, produce aberrations in scalp patterning. Eighty-five percent of patients with primary microcephaly have altered scalp hair patterning, indicating an early onset of abnormal brain development. Aberrant scalp patterning is also found frequently in association with established syndromes including Down syndrome. Thus, aberrant scalp hair patterning may be utilized as an indicator of altered size and/or shape of the brain prior to 12 weeks gestation. Early anomalies in development of the eye and of the face can secondarily affect hair patterning over the eyebrow and frontal area, presumably related to altered growth tension on the skin during the period of hair follicle formation. Gross anomalies in development of the ear can also secondarily affect hair patterning, especially in the sideburn area.
Full details of hair patterning anomalies plus quantitative differences in hair are found in Chapters 11 and 12.
Was this article helpful?
The best start to preventing hair loss is understanding the basics of hair what it is, how it grows, what system malfunctions can cause it to stop growing. And this ebook will cover the bases for you. Note that the contents here are not presented from a medical practitioner, and that any and all dietary and medical planning should be made under the guidance of your own medical and health practitioners. This content only presents overviews of hair loss prevention research for educational purposes and does not replace medical advice from a professional physician.