Combining various imaging techniques, an interdisciplinary team of scientists in Europe have developed a way to visualize and quantify early embryogenesis in zebrafish, according to a study published this week in Science.

"We want to turn all the verbal descriptions of biology into something that's going to be quantitative and formal," said embryologist and coauthor Nadine Peyriéras of the National Centre for Scientific Research (CNRS) in France. "We've been largely unable so far to do that."

The team used two imaging techniques that take advantage of the fact that signals are emitted when lasers interact with living tissues. One type of light emission, known as the third harmonic generation, provides information about the contours of the cell. The second harmonic generation, in contrast, provides information about mitotic spindles. Together, these two signals yielded a three dimensional view of developing zebrafish embryos, a model organism of vertebrate embryogenesis, allowing the researchers to measure cell size and shape and track cell lineage throughout the first 10 cell divisions.

As the researchers watched the embryos grow from single cells into the 1,000-cell stage, they learned that early embryogenesis is not nearly as synchronous or predictable as was believed.

"Asynchrony is the rule, and asymmetry is the rule," Peyriéras said. As early as the two-cell stage, "division is not synchronous, and cell volume is not the same either." These fluctuations result in a pattern of "pseudowaves," she said -- giving "the visual impression of the propagation of a wave."









N. Olivier, et al., "Cell lineage reconstruction of early zebrafish embryos using label-free nonlinear microscopy," Science, 329:967-71, 2010.


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