Lab 3. Physiology and Embryology
Friction ridge skin forms between the sixth and twenty-fifth week of fetal development. Prior to friction ridge formation, volar pads form on the palmar and plantar region of the fetal hand and foot. Volar pads are swellings of skin that regress as friction ridge development begins. As the volar pads recede, friction ridges begin to proliferate across the surface of the skin. As they spread out, minutiae form as follows: friction ridges that abruptly end create ending ridges; ridges that split into two create bifurcations; single ridge units that do not have time to form and extend create dots.