Oldest fibres of the lens are -

Ans. is 'a' i.e., In the nucleus "Oldest fibres of the lens are in the nucleus"Lens fibres* These are long protein fibers that are closely packed and parallel. They make up most of the lens volume and are laid horizontally, front to back, and concentrically like layers of an onion. As the lens fibres are formed through out the life, these are arranged compactly as nucleus and cortex of the lens.a) Nucleus: - It is the central part containing the oldest fibres, it consists of different zonesi) Embryonic nucleus :- Formed at 1-3 months of gestation, therefore consists the oldest primary fibres.ii) Fetal nucleus : - Lies around the embryonic nucleus and is formed from 3 months of gestation till birth.iii) Infantile nucleus:- Corresponding the lens from birth to puberty and surrounds the fetal nucleus.iv) Adults:- Corresponds to the lens fibres formed after puberty to rest of the life.b) Cortex:- It is the peripheral part containg the youngest fibres.