FSC239Y5 Lecture Notes - Lecture 6: Apocrine, Stratum Granulosum, Stratum Spinosum
Fingerprint Identification
What is a fingerprint?
Both the friction skin pattern formation found on human skin, as well as the
impression…..
The fingerprint impression or mark is a replication or transference of the
patterned skin. It can be likened to a stamp and ink pad. A stamp is placed into
the cushioned inkpad to accumulate ink on the elevated surfaces.
Established through the continuous agreement of friction ridge formations, I
sequences, having sufficient uniqueness to individualize.
The four premises of frictions ridge identification:
Friction ridges develop on the fetus in their definitive form prior to birth.
Friction ridges are persistent throughout life expect for permanent scarring, disease,
or decomposition after death.
Dates back to over 100 years for fingerprint identification.
Anatomy
Friction skin is also called volar skin.
Seen in primates
Assists in the ability to hold onto things or have traction.
Characteristics of the volar surfaces
No sebaceous (oil) glands
Sweat glands only
More sweat glands per square inch than other skin
No hair
Lack of pigmentation
Over-abundance of nerve-endings
Volar skin structure
Ridges made up of ridge units, each has one sweat gland and one pore.
As ridges grow they fuse together forming ridges.
All grow for the same amount of time but as different rates.
Dermis: thick foundation layer.
Epidermis: thin outer layer of 15-20 layers of dead cells that are shed off and replaces
continuously.
oLayer include stratum corneum (horny), stratum lucidum, stratum granulosum,
stratum spinosum, stratum basal.’
Friction ridge formation and differential growth
At 12 weeks when the primary friction ridges start to develop, patterns also start to
develop.
There are three sources of natural secretion on the human body: eccrine glans,
sebaceous glands, and apocrine glands. Only two are considered for fingerprint
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Document Summary
Both the friction skin pattern formation found on human skin, as well as the impression The fingerprint impression or mark is a replication or transference of the patterned skin. It can be likened to a stamp and ink pad. A stamp is placed into the cushioned inkpad to accumulate ink on the elevated surfaces. Established through the continuous agreement of friction ridge formations, i sequences, having sufficient uniqueness to individualize. Friction ridges develop on the fetus in their definitive form prior to birth. Friction ridges are persistent throughout life expect for permanent scarring, disease, or decomposition after death. Dates back to over 100 years for fingerprint identification. Assists in the ability to hold onto things or have traction. More sweat glands per square inch than other skin. Ridges made up of ridge units, each has one sweat gland and one pore. As ridges grow they fuse together forming ridges.
