The lenses in your eyes are the only transparent tissues in your body. If they were not transparent you could not see these words. How do these two lenses form? They are produced by some unique activity in a small number of cells, which activate a self-destruct program, which stops them from developing just before they are complete - leaving empty, but sustainable cells that transmit visible light.
The eye's lens is a biological marvel. It is dense, flexible and also clear. If it were imperfect in any way your vision would be warped or blurred, or you may be overcome by glare. If it had any hint of colour it would discolour your vision.
The lens is made of about 1000 layers of perfectly clear, living cells. It has no melanin and no blood supply. Cartilage is similar, yet it is translucent. This is because the cells in cartilage are grouped at many different angles, so light cannot pass evenly through them. The cells in the lens are stacked in layers, like bricks in a wall. Every cell is precisely . . .
The lenses in your eyes are the only transparent tissues in your body. If they were not transparent you could not see these words. How do these two lenses form? They are produced by some unique activity in a small number of cells, which activate a self-destruct program, which stops them from developing just before they are complete - leaving empty, but sustainable cells that transmit visible light.
The eye's lens is a biological marvel. It is dense, flexible and also clear. If it were imperfect in any way your vision would be warped or blurred, or you may be overcome by glare. If it had any hint of colour it would discolour your vision.
The lens is made of about 1000 layers of perfectly clear, living cells. It has no melanin and no blood supply. Cartilage is similar, yet it is translucent. This is because the cells in cartilage are grouped at many different angles, so light cannot pass evenly through them. The cells in the lens are stacked in layers, like bricks in a wall. Every cell is precisely aligned with those above and below it.
The lens has been described as a "biological crystal" because of its regular arrangement of cells. Each cell contains large molecules, called crystalline proteins, which form complexes with paracrystalline arrangements. This means the refractive index does not change inside the cell or from one cell to another, as light passes through.
Imagine you were as small as a molecule. You enter the womb and move to the developing human fetus. You travel to the head and arrive at the place where a lens is forming. You see millions of molecules swarming and clustering around a small, ball shape. Inside the ball, layer by layer, cells are forming and growing towards the centre of the ball. These cells reach the middle and then begin to elongate, losing their internal parts, and leaving nothing but an outer membrane and a thick solution of proteins called crystalline. This is the lens, and it is only one small part of the whole eye.
Normal body cells must be replaced or repaired every six months, but lens cells must function for a lifetime - without repair.
The lens is another wonder of God's creation.
Richard Gunther, Copyright 2005