The Incredible Eye
The eye stands as a testament to the effectiveness and magnitude of what can be achieved through natural selection. These extraordinary false-colour SEM images of the human eye were the brainchild of Professor Pietro Motta at the Institute of Human Anatomy of the University La Sapienza in Rome.
Top Left: Surface cells on the iris of the eye. Pigment cells (melanocytes, blue and brown) can be seen here, joined loosely together by connective tissue fibres (white). Smaller macrophage cells dot the surface.
Top Right: Lens of the eye. Lens cells run diagonally (dark green) across this field of view. The transparency of the lens (width 4 millimetres) is due to the absence of nuclei in these cells, and to the crystalline precision of their arrangement.
Centre: The inner surfaces of the iris and adjoining structures in the human eye. At far right (blue) is the edge of the pupil, the hole that allows light into the eye. Coloured mauve is the iris which controls the size of the pupil and therefore how much light will enter. The band of folds down the centre (red) are the ciliary processes.
Bottom left: The surface of the cornea. The matrix- like pattern (seen here) consists of individual flattened transparent cells. This is a stratified squamous epithelium which is 5 cell layers deep. Although full of nerves, there are no blood vessels in the cornea.
Bottom right: The human retina featuring the central fovea, a crater-like depression in the photosensitive layer of the eye. The foveal retina is the area of greatest visual acuity and contains only cone receptor cells. When an eye looks at an object, that part focused on the fovea is the portion most accurately registered by the brain.
All image credit goes to Professor Pietro Motta and Science Photo Library.