Fingerprints are primarily formed by the patterns of ridges and valleys on the skin of our fingertips. These patterns are created by the outermost layer of the skin known as the epidermis. Within the epidermis, there are specialized structures called dermal papillae which protrude into the epidermis and create the distinct patterns we see on our fingers.
The dermal papillae are made up of connective tissue and contain capillaries, which supply nutrients to the epidermis. The arrangement of these papillae is genetically determined, meaning that the unique patterns of ridges are formed during fetal development and remain unchanged throughout an individual’s life.
So, in summary, the ridges and patterns that make up fingerprints are the result of the interaction between the dermal papillae and the epidermis, which together create the unique textures we associate with individual fingerprints.