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Welcome to The Visible Embryo, a comprehensive educational resource on human development from conception to birth.

The Visible Embryo provides visual references for changes in fetal development throughout pregnancy and can be navigated via fetal development or maternal changes.

The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
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Home | Pregnancy Timeline | News Alerts |News Archive Sep 27, 2013

 

 

Video of experimental and simulation data from Manning's experiment, in which
two "droplets " of tissue join together, in a fluid-like manner, to form a single tissue.





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Model for tissue pattern formation in embryo development

A team of scientists has developed a model for studying tissue—specifically how it organizes into organs and layers during embryonic development.

Professor Lisa Manning, assistant professor of physics in Syracuse University's College of Arts and Sciences, wants to know if embryonic tissue behaves more like a solid or liquid — and why.

Her findings are the subject of a Sept. 25th article in the journal Interface (Royal Society Publishing, 2013) and may have major implications for the study of tissue pattern formation and malformation.

Central to their work was the question of whether embryonic tissue behaves more like a solid or a liquid—and why.

"We found that embryonic tissue was viscoelastic, meaning that it behaved like a liquid, if you pushed on it slowly, but like a solid, if you pushed on it quickly," says Manning, who co-wrote the article with Eva-Maria Schoetz, assistant professor of biology and physics at the University of California, San Diego; and Marcos Lanio and Jared Talbot, both researchers in Princeton University's Lewis-Sigler Institute for Integrative Genomics. "A mixture of cornstarch and water also behaves that way."


Manning and her team found that viscoelasticity was the result of "glassy dynamics" in cells, caused by overcrowding.

They discovered that cells within embryonic tissue were packed so tightly that they rarely moved—and when they did so, they expended considerable energy to squeeze past their neighbors.


She compares this behavior to riding on a subway. "If you're on a subway train that's not very crowded, it's easy to move toward the exit and get off the train," says Manning, an expert in theoretical soft condensed matter and biological physics. "But as more people get on the train, it takes longer to pick your way past them and exit. Sometimes, if the train is jam-packed, you miss your stop completely because you can't move at all."

Experimental and simulation data from Manning's experiment, in which two "droplets" of tissue join together, in a fluid-like manner, to form a single tissue.

Using state-of-the-art imaging and image analysis techniques, Manning and her team saw that each cell was crowded by what she calls a "cage of neighbors." A simple active-matter model, which they created, has enabled them to reproduce data and make predictions about how certain changes and mutations affect embryonic development.

"This is exciting because if cells slow down or generate more sticky molecules, the tissue can turn into a solid," says Manning, adding that such alterations can trigger malformations or congenital disease. "Our results provide a framework for understanding these changes."


Manning's work is rooted in that of another Princeton scientist, the late Malcolm Steinberg, who suggested more than 50 years ago that different types of embryonic tissue behave like immiscible liquids, such as oil and water.


"[This liquid-like behavior] helps tissue separate into layers and form structures, including organs,"says Manning, who joined SU's faculty in 2011, after serving as a postdoctoral fellow in the Princeton Center for Theoretical Science. "This type of work is fun because it involves knowledge from lots of disciplines, from soft-matter physics and materials science to cell and developmental biology."

Abstract
Many biological tissues are viscoelastic, behaving as elastic solids on short timescales and fluids on long timescales. This collective mechanical behaviour enables and helps to guide pattern formation and tissue layering. Here, we investigate the mechanical properties of three-dimensional tissue explants from zebrafish embryos by analysing individual cell tracks and macroscopic mechanical response. We find that the cell dynamics inside the tissue exhibit features of supercooled fluids, including subdiffusive trajectories and signatures of caging behaviour. We develop a minimal, three-parameter mechanical model for these dynamics, which we calibrate using only information about cell tracks. This model generates predictions about the macroscopic bulk response of the tissue (with no fit parameters) that are verified experimentally, providing a strong validation of the model. The best-fit model parameters indicate that although the tissue is fluid-like, it is close to a glass transition, suggesting that small changes to single-cell parameters could generate a significant change in the viscoelastic properties of the tissue. These results provide a robust framework for quantifying and modelling mechanically driven pattern formation in tissues.

Housed in The College, the Department of Physics has been educating students and carrying out research for more than 125 years. Graduate and undergraduate opportunities are available in fields ranging from biological and condensed matter physics, to cosmology and particle physics, to gravitational wave detection and astrophysics.

Original press releas: http://www.eurekalert.org/pub_releases/2013-09/su-spd092513.php