Epidermis

Epidermis is the outermost layer of skin. And therefore receives almost all nutrition from diffused Oxygen.

It is almost 95% keratinocytes.

Layers

From inside to outside

First, Basement Membrane, just between dermis and epidermis - a funny, non-cellular layer

Stratum Basale

Stratum germinativum (where proliferation of keratinocytes happen). Attached to basement membrane by hemidesmosomes (antibodies against these cause bullous pemphigoid)

Stratum Spinosum

The spines of this layer is a result of desmosomes holding cell membranes together. The remaining part that are not held tight can shrink and therefore a thorny appearance comes about.

Acantholysis is the loss of this cohesion between epidermal cells. “Acantho-” stands for spiny or thorny. And “lysis” is breakdown as usual.

Antibodies against desmosome proteins (desmoglein 1 and 3) are the cause of Pemphigus Vulgaris

Stratum Granulosum

Nucleus lost, cytoplasm granular with leftovers.

Stratum Lucidum

Member of thick skin.

Stratum Corneum

Anucleated corneocytes.