The epidermis is usually about 0.1 mm thick, and that is about
as thick as a piece of paper. On the palms and soles it is about
5 times that thick.
The barrier layer of the epidermis is the Stratum corneum.
the dermis is about 1 mm thick onthe eyelids, about 2 mm
thick on the arms and legs, and about 4 mm thick on the back.
The dermis is composed largely of Collagen , Elastin , Dermatin
Sulfate , _Chondroitin sulfate , and Hyaluronic acid.
The vascular plexes in the dermis are the Superficial and the
Deep. Most inflamation in the skin involves the Superficial.
The melanocytes supply about 36 surrounding epidermal cells
with melanin. Differnces in racial color are largely due to Sizes and
Grouping of melanosomes.
Eccrine sweat ducts are innervated by cholinergic nerve fibers.
Epidermal cells are held together largely by Dermosomes, Glycocalyx,
and Cellular interdigitation.
The epidermis is anchored to the underlying dermis by the hemi-desmosomes,
Anchoring filaments, and Anchoring fibrils.
It takes and epidermal cell about 15 days to traverse the stratum
spinosum, and about 15 days are spent in the cornified layer. The
time to traverse the entire epidermis is about 1-1.5 months.