The youngest lens fibres are present in:
**Core Concept**
The question is testing knowledge of the anatomy of the lens in the eye, specifically the process of lens fiber formation and the arrangement of lens fibers in relation to age. The lens is a unique structure composed of layers of lens fibers, which are formed from embryonic cells.
**Why the Correct Answer is Right**
The correct answer is related to the process of lens fiber formation. In the human eye, lens fibers are formed from the anterior (front) part of the lens epithelium, which is a single layer of cells. As the eye grows and develops, new lens fibers are formed at the equatorial region of the lens, and these fibers gradually move towards the posterior (back) part of the lens. The youngest lens fibers are therefore found at the posterior cortex of the lens. This process continues throughout life, resulting in the formation of a layered structure.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the anatomy of the lens fibers.
**Option B:** This option is incorrect because the nucleus of the lens is composed of older, more compacted lens fibers, not the youngest.
**Option C:** This option is incorrect because the anterior capsule of the lens is a thin membrane that covers the lens, but it is not where the youngest lens fibers are found.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the lens is a dynamic structure that continues to grow throughout life, and this growth affects the refractive power of the lens. This is why presbyopia occurs in older adults, as the lens loses its flexibility and ability to focus on close objects.
**Correct Answer:** D. The posterior cortex of the lens contains the youngest lens fibers.