September 25, 2013
Updated: September 26, 2013 12:52 IST
If nails are dead tissue, how are they able to grow?
EDWIN BRO KOMAGAL A.
Chennai
Nail is not made up of dead tissue. It is a part of a living tissue, like bone internally. Nail has a nail bed, and root from which it grows. It contains a thick keratin protein, which is equivalent to animal nails, or horns.
It grows from its root, like a hair grows from root. Cutting the hair is painless, but we do not call it dead tissue. It is the outgrowth of the living nail bed, which is meant to protect the soft tip of the finger from the injury, which we touch.
Patients with removed nail, subject themselves to severe injury, since a sense of deep sensation is passed by the nail to the underlying nervous tissue, called Pacinian corpuscles and free nerve endings underneath.
There is enormous blood circulation beneath the nail, capillaries which are visible in fair individuals, through the nail like a ground glass. There is a small semicircular white area under the base of the nail, called lunula, which is the growing part. Nail lives with the man. Many diseases are identified through nail, as it reflects health, and does not behave like dead tissue.
For example, diseases like anemia of various types, chronic arsenic poising, psoriasis, neuro-cutaneous markings, jaundice, etc. If it is a dead tissue it will not reflect the health. Only the terminal portion of the nail which protrudes away from the tip of the finger, has no sensation and no blood supply which is equivalent to a horn of animals.
DR. V. NAGARAAJAN
Professor Emeritus in Neuro Sciences
Tamil Nadu Govt Dr MGR Medical University
Madurai, Tamil Nadu
This story has been corrected for a typo error
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