Nails are the great tools located at the ends of your fingertips. They have many different uses, from scratching an itch to peeling the skin off of an orange. Nails can be used as defense weapons and are somewhat like sophisticated claws. Let's take a look at how nails grow and what they are made of.
Development of the Nail
Nails start begin to develop in the human embryo at about 10 weeks. Mounds of cell layers begin to form on the fingertips of the fetus, and at about 12 weeks the nail fold begins to develop. At 16 weeks a nail exists between thin layers of keratin. Keratin is the same protein that is contained in hair and skin. At 20 weeks the layers of cells on the fingertips are well developed and just before birth the keratin layer sloughs off and the nail is exposed. The development of the nail is a complex process taking the entire period of gestation to complete.
Parts of the Nail
The hard surface of the nail has three parts: the root, or base of the nail; the body, the hard exposed surface of the nail; and the free edge, the extreme tip of the nail. Other, more specific parts of the nail and the surrounding areas include the lunule, which is the white half-moon shape that you see at the base of the nail. The nail fold overlaps the base and covers the cuticle area. The eponychium, or cuticle, is at the top layer of the nail fold. The perionychium is the skin overlapping the sides of the nail or the nail wall. The hyponychium is the skin attached to the nail at the free edge.
How Nails Grow
Under the hard surface of the nail is the nail bed. The nail bed has two layers: the germinative zone and the deep underlying vascular layer of skin, the corium. The germinative zone is divided into two sections. The germinal matrix, located between the root of the nail and lunule, is where 90% of nail growth occurs. Cells are pushed out from the root of the nail by broadening and flattening. The sterile matrix is between the lunule and the free edge; the remaining 10% of nail growth happens here. Nail cells are pushed up from the sterile matrix, attach to the nail bed, and contribute to making the nail thicker.
Facts About Nail Growth
Your nails grow about 0.5 mm per week, and they grow faster in summer than winter. The longer the digit, the faster the nail grows. Fingernails grow four times faster than toenails. If you injure your nail, there is a 21-day delay in nail growth. The production of nail cells speeds up for the next 50 days, then decreases for 30 days. It takes a full 100 days until the normal volume of cell production and growth speed resumes. Maximum contour to the nail and smoothness will take a year to complete.
Nails are made of a protein called keratin, which is also found in skin and hair. The difference is the sulfur content. Keratin contains an amino acid called cysteine. Cysteine contains the sulfur atom. Two cysteines combine to form a disulfide bond. The number of these disulfide bonds in the keratin is what makes the difference between skin, hair and nails. Lots of disulfide bonds means very little flexiblity, like a nail. Fewer disulfide bonds results in more flexibility, like hair and skin.
Helping Nails Grow
You can strengthen your nails and encourage their growth by using products that reinforce the proteins found in your nails. Nail strengthening products tend to dry the nail, so use a good cuticle treatment to keep moisture levels in the nail healthy.
Keep your nails clipped and filed so the free edge remains intact. All nails are not created equal; your nails may have issues with dryness, softness or peeling and flaking. Environmental factors, occupation and physiology can also affect nail growth. Drink plenty of water and eat a balanced diet to maintain your overall health and wellness.