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...
In humans, nails grow at an average rate of 3 mm (0.12 in) a month. Fingernails require three to six months to regrow completely, and toenails require twelve to eighteen months. Actual growth rate is dependent upon age, sex, season, exercise level, diet, and hereditary factors.