Recent Articles of Interest

The epidermis is a hardened, stratified, squamous epithelium. Its density varies from 0.5 to 3mm. depending on its location. Being the most external layer of the skin, it is obviously an important place for microbial colonization.

The most common cell of the epidermis (constituting about 90% of all the cells of the skin) is the keratinocyte. New keratinocytes are continually being produced in the stratum basale. As they are moved towards the surface, they undergo a process known as keratinization.

This involves the synthesis of a special protein called keratin, and the subsequent death of the cell. The dead keratinized cells (known as squames) populate the outer layers of the epidermis with lipids that occupy the intercellular spaces and are slowly sloughed off - a process called desquamation. It has been calculated that the skin surface of the average adult is made of about 2 x 10 (9) squames. It takes between 2 and 4 weeks for the passage of a cell from the basal layer to the outermost layer of the skin, and as a consequence of this mechanism, it has been calculated that the stratum corneum is entirely renewed every 2 weeks.

The keratin present in cells defends the underlying tissues from heat, chemicals, and microbes. Melanocytes are the next most common cells of the epidermis. These have long thin projections that produce a brown-black pigment termed melanin. This pigment is then transferred to the keratonicytes where it blocks ultraviolet rays, thus defending the skin from its harmful effects, and preventing further actinic keratosis symptoms. The only other cells present in the epidermis are Langerhans cells (which are part of the immune response to microbial invaders) and Merkel cells (which are linked with sensitive neurons and are involved in the sense of touch).

Getting to know skin anatomy

The dermis has a highly complex structure that consists of:

1) Connective tissue containing collagen and elastin fibers conferring the skin tone; 2) Tiny finger-like projections (papillae) which protrude into the epidermis and have nerve endings sensitive to touch, heat and pain; 3) Hair follicles; 4) Arrector pili muscles for coordinating hair movement; 5) Sebaceous glands; 6) Sudoriferous glands; 7) Nerves; 8) Adipose tissue; and 9) Capillaries and veins.

Being aware of the bodily process behind acne problems is important in the search for solutions. On the keratin invested follicle canal, where the sebaceous glands reside, Proprionibacterium bactaria exists in symbiosis, feasting on and transforming the sebum secreted from the sebocytes cells before it reaches the surface of the skin. The nascent sebum is largely lipid in structure and also has DNA, RNA, proteins, and other cellular components that result from the breakdown of sebocytes themselves. Proprionibacterium acne is found only in sebaceous rich areas.

If the substrates in the follicular canals increase due to an active and large sebaceous system and sebum does not flow properly out of the canals, then colonization and high reproduction rates of Proprionibacterium acne will form. The resident bacterial flora produces biologically active molecules like histamine, extracellular enzymes and peptides, which may initiate the inflammatory reaction that characterizes acne breakouts.