During which months of fetal life do friction ridges begin to form on the human fetus?

Friction ridges, which are the unique patterns found on the skin of the fingers, palms, toes, and soles, begin to develop during the third and fourth months of fetal life. This process, known as dermal papillae formation, is crucial as these ridges become the basis for individual fingerprints. The development of friction ridges is influenced by genetic factors and is important for increasing grip and tactile sensation.

During the third and fourth months, the skin develops the necessary structures that will eventually form these distinctive patterns. By the end of this period, the basic layout of the friction ridges can be observed. This is significant in forensic science, particularly in latent print examination, as these unique patterns provide reliable means for personal identification.

The formation of these ridges does not occur in the earlier months because the skin is still undergoing foundational development, and it does not begin to mature until the later stages of fetal development. As a result, friction ridge formation is not recognized until the specified months when these features become evident.