Loop A curved line that begins and ends on the same axis. Rod A straight line that is generally found in the center of the fingerprint pattern area. Spiral A line that spirals out from the center of the fingerprint. Spirals are common to whorl patterns. A sweat-producing gland in the fingertip.
Every finger contains many sweat glands.
The moisture that they produce allows fingerprints to be electronically imaged. An arch that quickly rises and falls at a steep angle. Minutiae Points Line types contain common micro-features called minutiae. Most fingerprint classification systems analyze the minutiae points of the fingerprint pattern. Some examples of minutiae are the intersections of bifurcations, the endpoints of islands, and the center points of sweat glands.