Origin of cells for connective tissues of skull and face ...(eral nervous system or pigmentation did ...)

This paradox, he said, led him to wonder if different genetic programs were required to function in distinct embryonic precursors of these tissues. "In our new paper," he said, "we finally were able to re-examine some of the underlying assumptions that have led to the conventional wisdom about the source of the embryonic cell lineages that give rise to the skeleton and connective tissue of the head and face."

In the mouse embryo at eight days gestation, Weston and collaborators used high-resolution imaging and immunostaining techniques to identify and track the dispersal of cells known to jump start connective and skeletal tissue development. They were able to see clearly that these cells came from the non-neural layer of cells rather than from the neural crest. The same distinction also exists in chicken embryos during the first few days of gestation, Weston noted. "Looking at the right time is very important," he said.

Weston argues that this non-neural epithelium is indeed distinct from the neural crest, because its cells contain characteristically different molecules. He and colleagues dispute suggestions that this non-neural structure is simply a sub-domain of the neural crest. "These cells emerge at a different time in development and disperse in the embryo before neural crest cells begin to migrate," Weston said.

"New technologies let us see cell types more clearly than ever before," said Weston, a member of the UO's Institute of Neuroscience. "We previously had discovered that a molecule that marks cell surfaces in the non-neural epithelium reveals a very sharp boundary between this non-neural epithelium and the neural tissue connected to the neural crest. In this st
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