As an animal grows, maintaining the interactions between epidermal cells and touch-sensing neurons is critical to the animal's ability to sense touch.
Animals can sense touch as soon as they are born, even though the skin of a newborn is very simple. The epidermis of a newborn consists of only one or two sheets of epidermal cells, and a small number of touch-sensing neurons send axons to the epidermis. As newborn animals mature into adults, the skin grows to cover the much larger animal, the epidermis thickens by adding more layers of cells, and new touch-sensing neurons are born. In addition to growth and thickening, during this time special structures—like hair in mammals, feathers in birds, or scales in fish—form within the skin. We refer to this maturation as a "metamorphosis," a process between birth and adulthood when multiple tissues change at once. For example, the transformation of tadpoles into frogs is a metamorphosis. People undergo a similar metamorphosis as teenagers: as we develop from children into adults, many of our tissues grow and change. Our study aimed to understand how epidermal cells and touch-sensing neurons change as the skin undergoes metamorphosis.

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Go to source: https://kids.frontiersin.org/article/10.3389/frym.2019.00064