Hair and nail relationship.

Item does not contain fulltextHair and nails are often stated to have much in common in relation to their origin, anatomical structures, and common involvement in many diseases. Hair and nails are predominantly epithelial structures derived from primitive epidermis and made up of keratinous fibrils embedded in a sulfur-rich matrix. It was first noted early in the 20th century that the nail unit was comparable in several respects to a hair follicle sectioned longitudinally and laid on on its side. The epithelial components of hair follicle and nail apparatus are differentiated epidermal structures that may be involved jointly in several ways as congenital and hereditary anomalies and acquired conditions such as alopecia areata, lichen planus, iatrogenic causes, and fungal infection. Multielemental characterization of human hair and nails shows that even after sample washing, many elements are enriched in the surface of the nails

What is normal black African hair? a light and scanning electron-microscopic study

BACKGROUND: The hair of normal black Africans forms a mat of tightly interwoven hair shafts. The effect of this on the structure of the hair shaft and the response to grooming is unknown. OBJECTIVE: Our purpose was to use light and scanning electron microscopy (SEM) to examine the structure of Negroid-type hairs and effects of combing in black African volunteers. METHODS: Hair samples were collected, by combing, from Africans and compared with those from Caucasian and Asian volunteers. The volunteers had never used chemical treatments. Their hair had not been cut for at least 1 year and grooming had been limited to shampooing, drying, and combing. RESULTS: More than 2000 hairs in 12 African volunteers were examined by light microscopy. The hairs appear as a tight coiled springlike structure. Many shafts exhibited knots (10%-16% vs 0.15%) and appear broken compared with hair shafts from other ethnic groups. SEM of African hairs showed features consistent with repeated breaks of the shaft. Examination of hairs in situ showed interlocking of hair shafts. CONCLUSION: These observations provide an understanding of the physical nature of, and effect of combing on, black African hair