Most of this barrier role is played by the stratum corneum. CharacteristicsPhysical barrier: Epidermal keratinocytes are tightly linked by cell–cell junctions associated to cytoskeletal proteins, giving the epidermis its mechanical strength. Chemical barrier: Highly organized lipids, acids, hydrolytic enzymes, and antimicrobial peptides inhibit passage of external chemicals and pathogens into the body. Immunologically active barrier:  The humoral and cellular constituents of the immune system found in the epidermis actively combat infection. Water content of the stratum corneum drops towards the surface, creating hostile conditions for pathogenic microorganism growth. An acidic pH (around 5.0) and low amounts of water make the epidermis hostile to many microorganic pathogens. Non-pathogenic microorganisms on the surface of the epidermis help defend against pathogens by competing for food, limiting its availability, and producing chemical secretions that inhibit the growth of pathogenic microbiota.PermeabilityPsychological stress, through an increase in glucocorticoids, compromises the stratum corneum and thus the barrier function. Sudden and large shifts in humidity alter stratum corneum hydration in a way that could allow entry of pathogenic microorganisms. Skin hydration
The ability of the skin to hold water is primarily due to the stratum corneum and is critical for maintaining healthy skin. Skin hydration is quantified using corneometry. Lipids arranged through a gradient and in an organized manner between the cells of the stratum corneum form a barrier to transepidermal water loss. Skin color
The amount and distribution of melanin pigment in the epidermis is the main reason for variation in skin color in Homo sapiens.
An antilordotic brace commonly utilizes a plastic component that is contoured to closely fit the body. Antilordotic bracing subsequently reduces the athlete’s symptoms by decreasing the amount of stress on the low back, and allows a prompt return to sport for athletes. Typically, bracing is utilized for 6–12 weeks.In order for a brace to be effective, it must be worn every day for the required amount of time. Patients are given a brace schedule determined by their physical therapist that explains the amount of time the brace must be worn daily. A braces effectiveness increases with adherence to the bracing schedule. Patients that do not follow their bracing schedule are more likely to have their symptoms progress. Research has demonstrated that when braces are used as prescribed with full compliance, they are successful at preventing spondylolysis progression. Surgery
Most patients with spondylolysis do not require surgery but, if the symptoms are not relieved with non-surgical treatments, or when the condition progresses to high grade spondylolisthesis, then patients may require surgery. There are two main types of surgery for this condition:
Spinal fusion: This procedure is recommended when a set of vertebrae becomes loose or unstable. The surgeon joins two or more bones (vertebrae) together through the use of metal rods, screws, and bone grafts. The bone grafts complete their fusion in 4–8 months following the surgery, securing the spine in the correct position. The procedure is also used to treat spinal instability, fractures in the lumbar spine and, severe degenerative disc disease.