Fingerprints are commonly used to identify an individual. Research also suggests that fingerprints may provide information about future diseases an individual may be at risk for developing. Each fingerprint develops in phases as a fetus grows, forming a unique pattern of ridges, arches, whorls and loops.
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Finger Pad Development
The development of pads on the fingers and palms of fetuses marks the threshold for fingerprint development. This occurs during the second and third months of pregnancy, when the fingers are developing and the fetus is between 1 inch and 3 1/2 inches in size. The overall growth rate of a fetus and placement of the pads on developing fingers helps to determine where the future identifying skin indentations will be placed.
Skin Layer Growth
The third and fourth months of gestation find the skin of a fetus transforming from thin transparency to a waxy coating. It is during this time the middle layer of skin, called the basal layer, begins to outgrow the inner dermis and epidermis skin layers. The buckling and folding of this skin layer is partially responsible for the unique stresses in fingertip pads that become visible as development ensues.
Creation of Ridges
The first identifying marks that occur on a fetus’s skin are called ridges. Ridges are the faint lines on the fingertips that create the foundation of a fingerprint. A fetus touches surrounding structures -- her exact position in the womb and the density of the womb’s amniotic fluid determine how every individual ridge will form. The level of activity of a fetus and the general chaos of the conditions of the womb prevent fingerprints from developing the same way in fetuses.
By the time a fetus is six months old and approximately 12 inches in size, his fingerprints and footprints are fully developed. The ridges on a fetus’s fingertips have formed three main patterns by this time, categorized as arches, loops and whorls, with numerous patterns in between. These patterns are found on the fingertips, palms and soles and are used to grasp things.
Ridge patterns share two common characteristics found in every fingerprint: ridge end and bifurcation. The sequences of ridge end and bifurcation characteristics are different in every fingerprint. A ridge end consists of a ridge that ends abruptly; bifurcation is created by a single ridge that forks in two and continues on as separate ridges. These ridge characteristics may be a genetic roadmap for the predisposition of certain diseases. So far, researchers have found that people with diabetes have a much higher ridge count than those with normal glucose tolerance.