Pennsylvania State University, Department of Anthropology, United States.
Pennsylvania State University, Department of Anthropology, United States.
J Struct Biol. 2019 Jan 1;205(1):60-66. doi: 10.1016/j.jsb.2018.11.008. Epub 2018 Nov 22.
Human scalp hairs are often examined microscopically to study the variation and diversity among a range of visible morphological traits. In this study, we focused on the ultrastructure of human scalp hair within its keratinized matrix, emphasizing, the density and distribution of melanosomes, variation in cuticle thickness within populations, and the relationship of hair fiber ultrastructure with biogeographic ancestry. We used transmission electron microscopy (TEM) to visualize hair cross-sections and generate micron-scale resolution images for analysis of particle morphology and the layered hair matrix. Our results revealed considerable variation in all parameters examined, including the relationship of ultrastructure to biogeographic ancestry. Among the three metapopulations studied (European, African, and East Asian), we identified hair cross-sectional shape, cuticle dimensions, and melanosome distribution as traits that reveal statistically significant ancestry-related patterns. This study establishes trait patterns in hair morphology and ultrastructure among three biogeographically defined metapopulations to improve the current understanding of human variation in hair form and establish a foundation for future studies on the genetic and developmental bases of phenotypic variation in hair ultrastructure related to genotype.
人类头皮毛发经常被显微镜检查，以研究一系列可见形态特征之间的变异和多样性。在这项研究中，我们专注于人类头皮毛发的角蛋白基质内的超微结构，强调黑素体的密度和分布、人群中表皮厚度的变化，以及毛发纤维超微结构与生物地理祖源的关系。我们使用透射电子显微镜（TEM）来可视化毛发横截面，并生成微米级分辨率的图像，以分析颗粒形态和分层毛发基质。我们的结果显示，所有被检查的参数都存在相当大的变异，包括超微结构与生物地理祖源的关系。在研究的三个混合种群（欧洲、非洲和东亚）中，我们确定了毛发横截面形状、表皮尺寸和黑素体分布，这些特征揭示了与祖源相关的具有统计学意义的模式。本研究确立了三个生物地理定义的混合种群中毛发形态和超微结构的特征模式，以提高对人类毛发形态变异的现有认识，并为未来研究与基因型相关的毛发超微结构表型变异的遗传和发育基础奠定基础。
