Researchers at Washington State University's College of Veterinary Medicine have discovered that a microscopic skin structure, known as rete ridges, forms after birth in humans and certain animals such as pigs and grizzly bears. This finding challenges previous assumptions that these structures develop during fetal growth.
The study, published in Nature, found that while mice and non-human primates lack these features, animals with thicker skin like pigs, grizzly bears, and dolphins possess rete ridges similar to those in humans. These structures help anchor the outer layer of skin to the underlying dermal layer and play a role in maintaining elasticity and strength. As people age, these ridges flatten, causing the skin to become thinner and more susceptible to damage.
Sean Thompson, a doctoral student involved in the research, explained: "When most people look at the skin of different animals, they see differences in fur. Rete ridges lie under the surface of skin, however, so it wasn't until we looked closer that we discovered that animals with thicker skin, like pigs, grizzly bears and dolphins, have rete ridges like we do. In contrast, common biomedical models for humans like mice and non-human primates are furry and lack rete ridges."
By working with local farmers to collect pig tissue samples at various developmental stages, researchers determined that rete ridges form shortly after birth rather than before. Ryan Driskell from WSU commented: "We expected this structure to be established before birth, so seeing it emerge afterward was a surprise. That timing changes how we think skin architecture is built and why it may be possible to influence it later in life."
The team also identified bone morphogenetic protein (BMP) signaling as the biological pathway responsible for forming these structures. Maksim Plikus from the University of California, Irvine noted: "That BMP signaling drives rete ridges is exciting as it holds significant translational potential. Use of BMP proteins has already been FDA-approved for orthodontic applications, mapping the way for their use in aged skin and scars."
The findings could lead to new treatments aimed at slowing or reversing skin aging as well as improving wound healing and scar repair. There may also be benefits for livestock health by enabling breeding for specific skin traits adapted to different climates.
The research involved partnerships with local farmers; contributions from WSU's Bear Research Center; the University of Washington Birth Defects Research Laboratory; Spokane Dermatology; funding from the National Institutes of Health; and support from USDA Agricultural Research Service through its Resilient Livestock Initiative.
Driskell has filed a provisional patent related to these discoveries.
