Thick skin (which includes friction skin) has two principle layers: 

The Epidermis (E) is stratified (layered),  squamous (flat) epithelial tissue 5 layers thick and...

The Dermis is much thicker than the epidermis and consists of two layers - the Papillary layer (DPL) an area of loose connective tissue extending up into the epidermis as dermal pegs (DP) and the deeper reticular layer (DRL).
The primary function of the dermis is to sustain and support the epidermis.

The papillary layer (DPL) is made up of connective tissue with fine elastic fibres.  The surface area of this layer is increased by the
dermal papillae
(DP).   These fingerlike formations greatly increase the surface area for the exchange of oxygen, nutrients and waste products between the dermis and the epidermis.
Skin is one of the largest organs of the body. It is recognized as an organ because it consists of several types of tissues that function together. In addition, it includes millions of sensory receptors and an extensive vascular network. The skin is a protective, pliable covering of the body, one that is continuously replaced.  The Integumentary System includes the skin and the epidermal derivatives of hair, nails and glands.

The skin over most of the body is relatively smooth. 'Friction Ridges', however, are found on the digits, palms and soles.  They are called 'friction' ridges because of their biological function to assist in our ability to grasp and hold onto objects.  They have been compared to fine lines found in corduroy, however unlike corduroy,  ridges vary in length and width,  branch off, end suddenly and, for the most part, flow in concert with each other to form distinct patterns.  The ridge path can sometimes be quite fragmented...so much so as to show what appears to be individual ridge "units" present on the volar surface.  There are approximately 2,700 ridge "units" per square inch of friction skin.  Each ridge "unit" corresponds to one primary epidermal ridge (glandular fold) formed directly beneath each pore opening.   

Pore openings are present along the surface of the friction ridges.  They are fairly evenly spaced due to the fact that one pore opening along with one sweat gland exists for each ridge "unit".

Friction ridges are in their definitive form on the fetus before birth.  Once this blueprint has been established, in the stratum basale (generating layer) of the epidermis on the fetus prior to birth, it does not change except for injury, disease or decomposition after death.   Injury to the generating layer (Stratum basale) may affect the skin's ability to regenerate and scar tissue forms.

Location and size of pore ducts and pore openings along the surface of friction ridge skin are also in their definitive form before birth and do not change.
Skin is one of the largest organs of the body. It is recognized as an organ because it consists of several types of tissues that function together. In addition, it includes millions of sensory receptors and an extensive vascular network. The skin is a protective, pliable covering of the body, one that is continuously replaced.  The Integumentary System includes the skin and the epidermal derivatives of hair, nails and glands.

The skin over most of the body is relatively smooth. 'Friction Ridges', however, are found on the digits, palms and soles.  They are called 'friction' ridges because of their biological function to assist in our ability to grasp and hold onto objects.  They have been compared to fine lines found in corduroy, however unlike corduroy,  ridges vary in length and width,  branch off, end suddenly and, for the most part, flow in concert with each other to form distinct patterns.  The ridge path can sometimes be quite fragmented...so much so as to show what appears to be individual ridge "units" present on the volar surface.  There are approximately 2,700 ridge "units" per square inch of friction skin.  Each ridge "unit" corresponds to one primary epidermal ridge (glandular fold) formed directly beneath each pore opening.   

Pore openings are present along the surface of the friction ridges.  They are fairly evenly spaced due to the fact that one pore opening along with one sweat gland exists for each ridge "unit".

Friction ridges are in their definitive form on the fetus before birth.  Once this blueprint has been established, in the stratum basale (generating layer) of the epidermis on the fetus prior to birth, it does not change except for injury, disease or decomposition after death.   Injury to the generating layer (Stratum basale) may affect the skin's ability to regenerate and scar tissue forms.

Location and size of pore ducts and pore openings along the surface of friction ridge skin are also in their definitive form before birth and do not change.
Stratum corneum - consists of 25-30 layers of stratified (layered) squamous (flattened) dead keratinocytes (skin cells) that are constantly shed.
Stratum lucidum - is present only in thick skin (lips, soles of feet, and palms of hands). Little or no cell detail is visible.
Stratum granulosum - 3-4 layers of cell thick consisting of flattened keratinocytes.  At this level the cells are dying.
Stratum spinosum - several layers thick, consisting mostly of keratinocytes.  Together with the stratum basale it is sometimes referred to as the Malpighian layer (living layer).
Stratum basale - a single layer of cells in contact with the basement membrane.  These cells are mitotically active - they are alive and reproducing - the reason why it is often referred to as the generating layer.  Four types of cells are present in this layer:
Keratinocytes (90%) - responsible for waterproofing and toughening the skin
Melanocytes (8%) - synthesize the pigment melanin which absorbs and disperses ultraviolet radiation
Tactile cells - very sparse and function in touch reception
Nonpigmented granular dendrocytes - cells that ingest bacteria and foreign debris.
The primary function of the dermis is to sustain and support the epidermis.

The papillary layer (DPL) is made up of connective tissue with fine elastic fibres.  The surface area of this layer is increased by the
dermal papillae
(DP).   These fingerlike formations greatly increase the surface area for the exchange of oxygen, nutrients and waste products between the dermis and the epidermis.
Friction Skin - Epidermal Layers
Friction Skin - Epidermis/Dermis Junction
The boundary between the dermis and epidermis is a point of potential weakness where the two tissues may be separated from each other.  The fingerlike formations (or interdigitation) also serve to strengthen the epidermis/dermis junction.

As one ages the dermal papillae tend to flatten and may increase in numbers.  In this situation, each papilla appears to develop into a group...staying at the same overall size but individually much smaller. 
Cross-section of Friction Skin
Thick skin (which includes friction skin) has two principle layers: 

The Epidermis (E) is stratified (layered),  squamous (flat) epithelial tissue 5 layers thick and...

The Dermis is much thicker than the epidermis and consists of two layers - the Papillary layer (DPL) an area of loose connective tissue extending up into the epidermis as dermal pegs (DP) and the deeper reticular layer (DRL).
Sweat glands, or eccrine glands, are found over the entire surface of the body except a few small areas. They are most concentrated in the palms and soles of the feet.   The eccrine sweat glands in this skin section are well developed, and their ducts (dark staining) can be distinguished from the lighter staining secretory portions.

They are simple coiled tubular glands; they consist of a highly coiled secretory portion deep in the dermis, and a relatively straight duct conducts the secretions toward the surface of the epidermis.   Each duct opens in the centre of the ridge "unit" (cristae cutis). 

Eccrine sweat contains approximately 99% water and 1% solids.  The solids are half inorganic salt (mostly sodium chloride) and organic compounds (amino acids, urea and peptides).
Sweat Glands
Friction Skin
Friction Skin - Dermal Papillae