The Making of Fingerprints

As what I understand from reading several pregnancy books, fingerprints are formed during fetal development, when fetus is swimming in the amniotic fluid. That is why there is no identical fingerprints, not even in identical twins.

What get me to think though, why the prints are only formed in the fingers? and not other part of our skin?

In an explanation by anatomist Professor Ian Gibbins from Flinders University, the first signs of patterns on the fingers, palms and soles of the feet appear about 11 to 12 weeks after fertilisation, and the entire pattern of skin ridges is established by early in the fifth month of fetal life.

According to him, fingerprints are not formed by the ebbing and flowing of amniotic fluid. During early fetal development tissue on the fingers, palms and soles of the feet swells to form what are known as volar pads. These volar pads stop to grow when hands and feet continue to grow. As a result, the pads are reabsorbed back into the hand or foot. In this period, the interactions between our outer layer of the skin (epidermis) and the deep layer (dermis) results in ridges on the fingertips and toes. The timing of this process determines whether your dominant fingerprint ridge pattern is a whorl, loop or an arch.

There are complex and subtle genetic codes that produce factors determining which types of things will develop where. Take for instance, skin on our eyelids has different surface patterns than in our hands, different hair types grow on different part of our body, the number of sweat glands vary over our body and between different people. And this explains why fingerprints are only formed on our fingers, as we have differences in the structure of the skin all over our body.

In fact, fingerprints have a very high density of sensory nerve endings, which we use to judge the texture and shape of the objects we touch.