Aneurysm repair is a mechanical solution to the problem of progressive expansion of abdominal aortic aneurysm and the risk of rupture. Although open surgical repair, which has been the established
approach, is very effective, it carries substantial risks from the extensive surgical procedure. Endovascular repair was developed to reduce the risks associated with open surgery and to provide a
treatment option for patients who are not deemed to be surgical candidates.
A wave of ambitious social-network experiments is underway in the U.S. and Europe to track our movements, probe our relationships and, ultimately, affect the individual choices we all make. WSJ's
Robert Lee Hotz reports.
Human embryonic development depends on stem cells. During the course of development, cells divide, migrate, and specialize. Early in development, a group of cells called the inner cell mass (ICM)
forms. These cells are able to produce all the tissues of the body. Later in development, during gastrulation, the three germ layers form, and most cells become more restricted in the types of cells
that they can produce.
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