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Scientists have spent decades trying to understand what decides the exact spot where each hair begins.<\/p>\n
Simple rules for complex patterns<\/p>\n
The question matters for more than scientific curiosity. Hair follicles, feathers, and many types of scales<\/a> all begin as small embryonic structures called placodes.<\/p>\n Learning how placodes organize themselves could help researchers better understand how tissues form during development and how simple biological rules can create complex body patterns.<\/p>\n A new study points to a much simpler explanation than many researchers expected.<\/p>\n Scientists from the University of Geneva<\/a> (UNIGE) found that hair follicles may not need an elaborate biological program that tells each one exactly where to grow.<\/p>\n Instead, they appear to form naturally as cells respond to chemical signals while moving through developing skin.<\/p>\n A long-standing idea<\/p>\n For years, the leading explanation for hair follicle formation in laboratory mice, Mus musculus, was known as the expansion-induction model.<\/p>\n According to this idea, each newly formed placode releases a chemical that prevents nearby placodes from forming. <\/p>\n As the embryo\u2019s skin expands, regions eventually move beyond the reach of that signal, allowing new placodes to develop.<\/p>\n Although this model has been widely accepted, researchers had never shown that it could explain hair pattern formation across different mammal species<\/a>.<\/p>\n Cells organize themselves<\/p>\n The research team was co-led by Athanasia Tzika<\/a> and Professor Michel Milinkovitch<\/a> at UNIGE\u2019s Faculty of Science. They explored a different possibility based on chemotaxis.<\/p>\n Chemotaxis is the ability of cells to move toward or away from chemical signals. It is already known to help guide white blood cells to areas of inflammation.<\/p>\n Using a mathematical model, the scientists examined how mobile dermal cells interact with an attractive chemical signal produced by the epidermis.<\/p>\n They simulated skin growth in embryos and watched how placodes developed over time.<\/p>\n Order without a blueprint<\/p>\n The results showed that this simple process produced the same pattern of hair follicle formation previously explained by the older expansion-induction model in laboratory mice.<\/p>\n \u201cOur findings show that the observed patterns do not require a complex system telling each placode where to form,\u201d explained Muhamet Ibrahimi<\/a> and Ebrahim Jahanbakhsh<\/a>, researchers in the Department of Genetics and Evolution.<\/p>\n \u201cInstead, placodes emerge spontaneously from local interactions between cells and chemical signals.\u201d<\/p>\n Explaining the mouse<\/p>\n The researchers then asked whether the same idea could explain another animal with a very different coat pattern. <\/p>\n They turned to the spiny mouse<\/a>, Acomys dimidiatus, a rodent<\/a> whose hair follicles grow in an unusually regular and highly organized arrangement.<\/p>\n The traditional expansion-induction model could not account for this distinctive pattern.<\/p>\n The team combined their mathematical model with experimental data gathered from three-dimensional images of developing embryonic skin.<\/p>\n Differences across species<\/p>\n The researchers found that the same chemotactic process successfully recreated the spiny mouse\u2019s hair follicle pattern.<\/p>\n The model successfully reproduced the pattern when the researchers incorporated the species\u2019 unique biochemical properties and skin growth characteristics.<\/p>\n The findings suggest that different species may rely on the same basic biological process while producing very different results. <\/p>\n Small differences in how cells communicate and respond during development appear to produce these differences.<\/p>\n Building complex tissues<\/p>\n Many structures in nature appear highly ordered, yet they often arise from countless local interactions rather than from a central controller. <\/p>\n Biologists have seen similar self-organizing behavior in processes ranging from early embryo development to the formation of blood vessels and branching organs.<\/p>\n The new study adds hair follicle development to that growing list. Rather than requiring detailed instructions for every follicle, embryonic skin is capable of organizing itself.<\/p>\n \u201cOur work suggests that simple cellular interactions can generate the remarkable diversity of tissue architectures observed throughout evolution<\/a>,\u201d concluded Tzika.<\/p>\n \u201cThe differences observed between species therefore result from the same self-organization process, but with variations in the interactions between cells and chemical signals.\u201d<\/p>\n The full study was published in the journal Proceedings of the National Academy of Sciences<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Hair begins forming long before an animal is born. As a mammal develops inside the womb, tiny structures…\n","protected":false},"author":2,"featured_media":546459,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82],"class_list":["post-546458","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ie","tag-ireland","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/546458","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=546458"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/546458\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/546459"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=546458"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=546458"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=546458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}