The Critical Stage of Friction Ridge and Pattern Formation

This study provides an enhanced understanding of the biological structure and development of friction ridge skin for the latent print examiner who is called upon to explain the scientific principles of latent print identification as based on permanence and uniqueness. Cellular attachments ensure permanence, while variable stresses and cellular distributions account for individuality on all “three levels” of detail. Volar patterning is dependent upon the tension across the surface of the developing skin during a critical stage of approximately 10.5 to 16 weeks estimated gestational age. Fingerprint ridge counts are predominantly affected by two combined timing events: the onset of epidermal cellular proliferation and the timing of the regression of the volar pads. Fingerprint pattern types are predominantly affected by the symmetry of the volar pad.