Stem cells taken from the back of the eye could eventually be used to restore normal vision in people with sight problems, researchers have said.
According to BBC News Online, human retinal stem cells regenerated when they were transplanted into the eyes of mice and chicks, scientists at the University of Toronto found.
They now plan to see if the same happens in diseased eyes in the hope of eventually treating humans.
The retina sits at the back of the eye and is where light rays are turned into images.
It acts like the film in a camera to capture images, transform them into electrical signals, and send these signals to the brain.
The retina contains millions of cells called photoreceptors (divided into rods and cones), which contain visual pigments.
When light strikes these pigments, they briefly lose their color. This bleaching process triggers nerve impulses, which are transmitted to your brain.
The researchers took retinal stem cells from human cadavers and transplanted them into the eyes of one-day-old mice and chicks.
The transplanted cells developed into photoreceptor cells.
Lead researcher Brenda Coles said: "When their eyes fully developed, the human cells survived, migrated into the sensory part of the eye and formed the correct cells."
The are now exploring whether the retinal stem cells from these healthy mice will continue to develop when transplanted to mice with diseased eyes.
This will help them find out whether retinal stem cells can be used to treat degenerative diseases of the retina such as retinitis pigmentosa and macular degeneration, which are among the most common forms of blindness in developed countries.
These diseases affect rods and cones, the photoreceptor cells at the back of the retina, but the nerve cells in front of them usually remain intact.
Coles said, "We're starting with mice to see if they can overcome the genetics involved in disease.
Stephen Minger, director of the stem cell biology laboratory at King's College, London, said: "As a first step, I think this paper is superb.
He said it would be important to prove that the implanted cells functioned normally and that they also worked in disease states.
Also, it has yet to be determined whether enough of the required number of cells could be generated to repair damage in humans, he said.

Researchers at the University of Manchester and Chernogolovka, Russia have discovered the world's first single-atom-thick fabric, which reveals the existence of a new class of materials and may lead to computers made from a single molecule, brightsurf.com said.
The team led by Professor Andre Geim at the University of Manchester, has succeeded in extracting individual planes of carbon atoms from graphite crystals, which has resulted in the production of the thinnest possible fabric--graphene.
The resulting atomic sheet is stable, highly flexible and strong and remarkably conductive. The nanofabric belongs to the family of fullerene molecules, which were discovered during the last two decades, but is the first two-dimensional fullerene.
The researchers concentrate on the electronic properties of carbon nanofabric. By employing the standard microfabrication techniques used, for instance, in manufacturing of computer chips, the team has demonstrated an ambipolar field-effect transistor, which works under ambient conditions.
They found that the nanofabric exhibits a remarkable quality such that electrons can travel without any scattering over submicron distances, which is important for making very-fast-switching transistors.
In the quest to make the computer chip more powerful and fast, engineers strive to produce smaller transistors, shortening the paths electrons have to travel to switch the devices on and off. Ultimately, scientists envisage transistors made from a single molecule, and this work brings that vision ever nearer.
In terms of applications, the sort of quality demonstrated by graphene can only be compared with that demonstrated by some nanotubes. Professor Geim commented:

Platypus is native to Australia, and belongs to a primitive group of mammals called the monotremes.

Everyone knows that the duck-billed platypus is pretty strange. But it seems this mammal's eccentricities extend beyond its famous bill, and habit of laying eggs, to the way its genes determine sex, nature.com reported.
Not content with one pair of sex chromosomes, the platypus (Ornithorhynchus anatinus) has five. This is the largest number found in mammals so far, and also hints that the sex determination systems of birds and mammals may be linked.
The platypus is native to Australia, and belongs to a primitive group of mammals called the monotremes, along with only two other surviving species: the long-beaked and short-beaked echidnas.
Monotremes were the first group to branch off after mammals evolved 210 million years ago. Their egg-laying shares a common origin with birds and reptiles, although the bill is thought to have evolved independently.
The platypus has 26 pairs of chromosomes in total, compared with the 23 pairs present in humans. But researchers had long been confused about which ones are autosomal (inherited equally by males and females), and which ones determine sex.
Frank GrŸtzner of the Australian National University in Canberra and his colleagues used fluorescent tags to study the animal's chromosomes. They were amazed to find that five separate pairs, which join together in a chain during cell division, determine an individual's sex.

The small group of genes long believed to cause Down syndrome are unlikely to be the real culprits, according to recent research in mice, nature.com said.
Down syndrome occurs in around 1 in 700 live births. The vast majority of people with the condition are born with three complete copies of chromosome 21 instead of two. But a small proportion of individuals with Down syndrome have only certain portions of chromosome 21 in triplicate.
Although chromosome 21 contains over 200 genes, comparison of people with complete and partial repetition led researchers to believe that most features of Down syndrome are caused by a so-called 'critical region' of chromosome 21, which contains just 30 or so genes. This idea has held sway for the past 30 years.
Now researchers have used genetically engineered mice to disprove the theory. They bred mice with one, two and three copies of the mouse equivalents of genes from the critical region of human chromosome 21. They then compared visible, Down-like characteristics of these animals, such as face, head and growth measurements, with those from a known mouse model of Down syndrome.