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This page contains the supplemental animations for

Wertheim, Kasey; Maceo, Alice, "Friction Ridge & Pattern Formation During the Critical Stage," Journal of Forensic Identification, Volume 52, Number 1.

NOTE: Download times vary depending on your connection speed.  These animations are fairly large, and can take several minutes to load before they display properly.  This may include one round of particularly slow progression, followed by faster rounds of animation to demonstrate the concept properly.

Figure 6 (709K)
This animation represents the currently accepted theory that localized cellular proliferations grow together into what subsequently appear as ridges at the epidermal / dermal junction at approximately 10.5 weeks estimated gestational age.

 Figure 7 (821K)
This animation represents the consensus of the literature in demonstrating the theoretical formation of minutia arising from expansion of the volar surface and the tendency of volar skin during the critical stage to remain continuously ridged.  Once secondary ridge formation begins (the red ridges in this animation) at about 16 weeks EGA, the minutia becomes set and the ridges will only increase in size during maturity.

Figure 16 (93K)
This animation represents the life of a volar pad, from before formation at about 6-7 weeks until after "regression," at about 16-17 weeks.  During this time the finger grows significantly.  The volar pad in this animation regresses symmetrically.

Figure 19 (311K)
Ridges form in three distinct locations on the end joint of the finger and converge.

Figure 20 (277K)
Deltas form where three converging ridge fields meet.

Figure 21 (322K)
Large count pattern formation: ridges form in the center first and proceed outward before being met by the other ridge fields.

Figure 22 (248K)
Small count pattern formation: ridges form on the outer perimeter of the pattern area and proceed inward until the last instance, when ridge formation begins at the apex of the pad.