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...
A big toenail can take 6-12 months to grow back in. I would check to see if there is a fungal infection that caused the nail to fall off. If so, it will be much easier to treat while the nail is gone before it grows back. They are common, but stubborn to get rid of.