In human and nonhuman primates, however, the SVZ has a massively expanded outer region, known as the outer subventricular zone (OSVZ). About 20 years ago, scientists presumed that the OSVZ also contained stem cells, but until now they have lacked evidence.
In the current study, lead authors David V. Hansen, PhD, a postdoctoral fellow, and Jan H. Lui, a graduate student in the Kriegstein lab, examined the OSVZ, using new labeling and tracking techniques to follow individual cells and their progeny over time in cultured tissue slices from fetal cortex tissue that had been donated for research.
They characterized two kinds of cells within the region -- both the novel neural stem cell and its daughter cell, known as the transit amplifying cell. The stem cell closely resembles the radial glial cell in structure and behavior and, like the radial glia, has radial fibers which newborn neurons migrate along up to the neocortex.
The region is a busy hub of cell proliferation. The stem cell undergoes asymmetrical cell division, giving rise to two distinct daughter cells -- one a copy of the original stem cell, the other a transit amplifying cell. The transit amplifying cell undergoes multiple rounds of symmetrical divisions before all of its daughter cells begin the process of differentiating into neurons.
"We are very interested in understanding how these modes of division are regulated," says Kriegstein. "We suspect that faults in cell-cycle regulation account for a variety of developmental brain diseases."
More broadly, he says the team wants to unders
|Contact: Jennifer O'Brien|
University of California - San Francisco