Posts from the ‘stem cells’ Category
All vertebrates’ eyes emerge from a single group of cells, called the eye field, located in the middle of the brain. The eye field cells evaginate to form two optic vesicles, which eventually give rise to two retinas, one on either side of the brain.
Top image: In a ~5 somites embryo, eye field cells are stained red, and forebrain cells are outlined in green (upper left). A few hours later, in a ~10 somites embryo, the eye field (green) separates into two optic vesicles. At the same embryonic stage, the dorsal telencephalon, which sits atop the evaginating eyes, is labeled blue (bottom left). In both of these images, a midline positioned cross outlines the apical surface of the optic vesicles and the ventricular space. The animation follows the development of this same surface as the eyes emerge from the brain.
Sunrise in the Eye
Bottom image: Once the basic shape of the eye is specified, cells within the optic cup differentiate, populating the retina with neurons that sense light and refine the visual information before it is transmitted to the brain. In fish and amphibia, retinal stem cells are maintained throughout the animal’s lifetime in a stem cell niche located adjacent to the lens (yellow). Here in situ hybridization of a zebrafish eye (from a ~ 3-day-old larva) reveals gene expression patterns that distinguish retinal stem cells (red) from the cells that are becoming neurons (purple). By comparing gene expression patterns within the retinal stem cell niche in normal and mutant eyes, we gain insight into how stem cells turn into neurons.
Eyes are not only amazingly complex, but are reducibly so!
Look at that sad bastard.
I’ve been genetically blessed when it comes to baldness. Both sets of grandparents kept hair well into their 80’s, and my dad probably has thicker hair than I do. No grey, just plenty of hair. This mouse can’t say the same thing.
This type of mouse is genetically modified so that it can’t produce hair (in addition to having absolutely no immune system whatsoever, which makes this research possible). Japanese scientists have used human and mouse stem cells implanted along with tiny nylon tubes to stimulate fully functional hair growth in these nude mice. It even stands on end when the mouse is cold! Which is probably a lot, since it’s bald!
Imagine a future where blood vessels, skin grafts, hair and more are regrown with targeted injections of cells. That future is going to be awesome. More on these regenerative techniques here.