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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 ' million visitors each month.

WHO International Clinical Trials Registry Platform
The World Health Organization (WHO) has created a new Web site to help researchers, doctors and patients obtain reliable information on high-quality clinical trials. Now you can go to one website and search all registers to identify clinical trial research underway around the world!




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Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.
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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 weeks 0 - 40 and follow fetal growth
Google Search artcles published since 2007
August 26, 2011--------News Archive

A Question of Gene Silencing
Researchers have found a new way to selectively turn off genes that don't code for proteins which will help identify each gene's function, and perhaps identify cancers.

Scented Products Emit Hazardous Chemicals
Chemical sleuthing has uncovered that fragrance in consumer laundry products contains hazardous chemicals. Some which are even carcinogens.

August 25, 2011--------News Archive

Human Stem Cells Made From Amnionic Fluid
Human epithelial cells transplanted from human amnionic fluid reduce pulmonary fibrosis, and even stimulate lung regeneration in mice.

Scale Models Rule
Body patterns stay in sync with size as an embryo grows into an adult. Observed in the wing of the fruit fly, these patterns most likely exist in all organisms.

Chronic Disease Caused by Fat Cells?
Fat cells in people with metabolic syndrome have biomarkers for insulin resistance and chronic inflammation, conditions in diabetes and cardiovascular disease.

August 24, 2011--------News Archive

In the Early Life of An Embryo, Chaos Lurks
A calcium wave sparks embryonic cell division, doubling as a synchronizer of all further cell division in order for chaos to be reined in and ordered growth to persist.

Smoking Affects Fetal Infant Brain Worse than Feared
Researchers pin-point smoking specifically and find a 40% increase in damage to the fetus.

August 23, 2011--------News Archive

Boys Reach Sexual Maturity Younger and Younger
The phase between being physically but not socially adult is getting longer.

When Cell Fishing Games Go Wrong
Trial-and-error "fishing" for DNA in the nucleus may be the most important cause of female infertility.

A Sticky Egg Captures The Sperm
A sugar molecule makes the outer coat of a human egg 'sticky', which is vital for enabling the sperm and egg to bind together.

At Last, Reason Why Stress Damages DNA
Adreneline produced by chronic stress, degrades the protein p53 which is considered a tumor suppressor protein and "guardian of the genome."

August 22, 2011--------News Archive

The Basis for Head and Sex Organ Deformities
Data reveals a possible therapy using vitamin B2 to reverse enzyme defects is specific areas of fetal development.

Mother’s BMI Linked to Fatter Babies
Babies of mothers with a higher pre-pregnancy body mass index (BMI) are fatter and have more fat in their liver, a study has found.

Celiac Disease May Explain Some Women's Infertility
A recent study found increased rates of celiac disease in women who present with unexplained infertility.

WHO Child Growth Charts

Researchers have discovered that newly fertilized cells narrowly avoid falling into chaos. Simulating the division and duplication of embryonic cells - oscillation - the team found the process is regulated by a wave of calcium beginning at the site of fertilization. This picture represents a fast calcium wave sweeping across an embryo at a speed of 1 millimeter every four minutes. When oscillation is synchronized by calcium, the embryo divides evenly, about every 40 minutes. (Image by K.C. Huang)

Research based at Princeton University has revealed that newly fertilized cells only narrowly avoid degenerating into fatal chaos. At the same time, scientists have discovered that embryos have acquired a mechanism to contain this dangerous instability, a finding that could help biologists unravel other mysteries about the first hours of life.

A team led by Princeton Professor of Molecular Biology Ned Wingreen reported recently in the journal PLoS Computational Biology that contrary to the idea that embryonic cells develop in natural synchrony, they are prone to descend into disarray. Without stabilization, cells develop on different schedules, and many stop developing altogether, which threatens the embryo's survival.

This lurking state of disorder was revealed through computer models made of the embryo cell cycle. The repeated division and duplication of cells that transforms a single fertilized egg into a full-grown organism is known as the cell cycle.

Scientists already knew that embryonic cell cycles are initiated by a swift wave of calcium, beginning at the fertilization site, which prompts the embryo's cells to divide and duplicate - or oscillate, in biological terms.

A assumption among scientists had been that once begun, the impulse to oscillate would ripple across the embryo and set the stage for multiple rounds of cell divisions to occur in sync.

Wingreen and his colleagues found, however, that the natural spread of oscillation is unstable and could result in an erratic patchwork of missed and incomplete cell divisions. They predicted that cell activity instead has to be triggered throughout the embryo at almost exactly the same time.

The researchers' simulation of oscillation was the first indication that the fast-moving calcium wave known to spark cell division doubles as a synchronizer, setting cells to the same developmental timetable. This finding revealed a crucial role for the somewhat puzzling existence of the calcium wave, as well as a new level of sophistication in how embryos function.

"We didn't have to go searching for chaos, it just came right out at us," Wingreen said. "When the dust settled, it became clear that cell-cycle oscillation, while remarkably uniform in the end, does not come by that harmony on its own, especially not in anything as big as an embryo, which is much larger than a typical cell. But then the question became, if there's this potential for chaos, how does the system avoid it? It turns out that the system needs the calcium wave to avoid chaos and that wave is activated surprisingly fast."

The embryo's need for stabilization and the dual role of the calcium wave illuminates the intricacy of developing embryos, as well as the impressive ability of embryos to prevent their own destruction, according to James Ferrell, Stanford University professor of chemical and systems biology. The formulas Ferrell developed from experiments on African clawed frog embryos describe how embryos divide and replicate in timed cycles during early development, and became the basis for the Princeton reasearch.

"One of this group's conclusions is that chaos lurks not far from where the system normally functions, like a monster in the corner, and that it matters to have synchronicity established quickly to prevent it. That's not something we had initially thought about," said Ferrell, who had no involvement in the Princeton-led research, but is interested in testing the results experimentally.

"They present a nice story of how evolution has come up with a way to do things as fast as is needed to avoid chaos, but not too much faster. It's deepened our appreciation of what is happening in the biological system, and is a good example of how theory and careful modeling can reveal functions that might not appear in experiments."

Wingreen, a theoretical biologist and associate director of Princeton's Lewis-Sigler Institute for Integrative Genomics, initiated the project after noticing that existing cell-cycle formulas and models, such as Ferrell's, did not explain how embryos keep cell activity synchronized across their considerable girth.

Embryos are huge, about 10 to 100 times larger than a normal cell, and at that size oscillation would not necessarily fan out evenly from the point of fertilization. Instead, it would be vulnerable to any bump in the cellular road and could splinter into patches of disarray, Wingreen said.

In theory, Wingreen believed chaos could be avoided if oscillation spread quickly enough. But the cell cycle is driven by an intricate exchange of proteins with its own schedule. Wingreen doubted that this activity could spread itself across an expansive embryo fast enough, especially as the embryo grows. He wanted to take the embryo's size into account as a factor in the spread of cell activity, which no published cell-cycle models had considered.

Wingreen and the paper's lead author, Scott McIsaac, a doctoral student in Princeton's Lewis-Sigler Institute, altered Ferrell's cell-cycle equations so that oscillation would spread across the expanse of an embryo. They worked with co-author K.C. Huang, Stanford assistant professor of bioengineering, to solve the revised formulas using a three-dimensional model. Co-author Anirvan Sengupta, a professor of physics and astronomy at Rutgers University, characterized and analyzed the various instabilities that might occur as the simulated embryonic cells divided in the computer model.

"We had no clear idea of what adding a spatial element would produce," Wingreen said. "I was interested if there was an inhomogeneous element to cell-cycle oscillation, if the cells in fact did not all act in unison. My training is in physics, and I know that whenever you add a new dimension, interesting things can happen. I had a feeling something would happen if we ran these formulas in a spatially extended system."

The initial simulation tested how cell activity would spread through the embryo solely by diffusion. Oscillation indeed found its way across the cell, but disorder took root almost instantly. Cells divided at different speeds, with many left undeveloped by the end of the cycle. As the simulation went on for 200 minutes, the mayhem grew worse. A real embryo would not survive this breakdown, or would at least be left with severe developmental problems, Wingreen said.

Wingreen and McIsaac began to suspect that the calcium wave had a role in keeping the cellular peace. Although known to spark cell cycles, the full purpose of the calcium wave had previously had some shadow of mystery, Wingreen said. But once the team ruled out that cell activity could self-regulate, they knew something else brought order to the developing embryo. The calcium wave -- which spreads across the embryo rapidly following fertilization -- seemed a likely candidate.

The researchers then simulated cell division with fast and slow calcium waves. Slow waves creeping at 1 millimeter every 10 minutes opened the door for havoc. However, when sped up in the simulation to travel a millimeter in four minutes, the calcium wave synchronized cell activity, and the embryo developed normally. The simulation exposed the calcium wave as not only an initiator of embryo development but also a regulator of that activity.

If the calcium wave doubles as a regulator, then it could have other functions. Moreover, other mechanisms that seemingly serve one purpose may also have others. These possible extra duties could be behind other happenings in embryo cells that are not well understood, said Eric Wieschaus, the Squibb Professor of Molecular Biology at Princeton and a 1995 Nobel Prize winner.

"The fact that the system generally doesn’t devolve into chaos might mean that embryos have developed additional mechanisms that we don't know about. It would be interesting to know what those mechanisms are," Wieschaus said.

"From my own standpoint, the paper makes me want to check back through mutant lines that disrupt development and have never been fully described or understood, but might be affected in this process. This model gives a sense of what to look for, and that is always valuable."

Just as the experiment-based models developed by Stanford's Ferrell fueled Wingreen's work, Wingreen hopes his models can guide further study of embryo development in the laboratory. He said the next steps are to reproduce the simulations in actual embryos, and to test the limits of calcium-wave synchronization to learn if it holds up when development on one side of an embryo is slowed, or if the two halves of a split embryo would remain coordinated.

"These are all experimental steps," Wingreen said. "My group does theory and modeling, so our hope is that we've put the ball back in the experimentalists' court."

The research, reported in the July issue of PLoS Computational Biology, was funded by grants from the National Science Foundation and the National Institutes of Health.

Original article: http://www.princeton.edu/main/news/archive/S31/37/87G18/