cortices. 1  1a (1) : the outer or superficial part of an organ or bodily structure (such as the kidney, adrenal gland, or cerebellum or a bone); especially : cerebral cortex (2) : the proteinaceous usually pigmented layer of a hair below the cuticleb : the outer part of some organisms (such as paramecia)
If a toenail has completely fallen off, it can take up to 18 months for it to grow back. A toenail can take longer to grow back if the nail bed has permanent damage. In some cases, old nails do not completely fall off, and they act as a protective...
Torn or Detached Nail Facts. 1  Fingernails and toenails, like hair, are composed of protein and fat and are not live tissue. 2  Nails grow a bit more than one-tenth of an inch per month and require three to six months to completely regrow. (Toenails grow more slowly than fingernails.) Nails are produced by the nail matrix cells that reside in the moon shaped whitish area (lunula) at the base of the nail.