Biologists at the University of Geneva (UNIGE) have found that the ordered patterns of hair follicles on mammalian skin form during embryonic development through the simple directed movement of cells in response to chemical signals. The findings, published in the scientific journal PNAS, challenge the long-held theory that a detailed genetic blueprint or a strict system of inhibitory signals is needed to create complex biological patterns — whether hair, feathers or scales, the website infohub.kz reports.
The leading hypothesis had been the expansion-induction model: each nascent follicle (placode) releases a substance that blocks neighbors from appearing too close, until the embryo's skin stretches. But this theory could not explain the full diversity of natural structures.
A team led by Athanasia Tsika and Michel Milinkovitch of the Department of Genetics and Evolution focused on chemotaxis — the directed movement of dermal cells toward chemical attractants released by the upper layer of skin.
The mathematical model the researchers built showed that follicles arise spontaneously through local cell interactions, without complex external instructions. The simulation successfully reproduced hair growth not only in ordinary laboratory mice (Mus musculus) but also in spiny mice (Acomys dimidiatus), whose follicles arrange themselves in unusually neat rows.
According to the scientists, the diversity of tissues in the animal kingdom is explained by variations in the rate of skin growth and in the chemical properties of one and the same self-organization mechanism.