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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.


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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
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September 23, 2011--------News Archive

Brain Wiring Continues Well Into Our 20s
The human brain doesn’t stop developing at adolescence, but continues well into our 20s, research from the University of Alberta demonstrates.

Vitamin D Deficiency Linked With Severe Asthma
Children with severe therapy-resistant asthma may have poorer lung function and worse symptoms due to lower levels of vitamin D in their blood.

Reprogramming Muscle Stem Cells to Regenerate
Researchers at the University of California, Berkeley, have turned back the clock on mature muscle tissue, coaxing it back to form new muscle.

September 22, 2011--------News Archive

BPA Changes In-Vitro Egg, Risking Down Syndrome
Bisphenol A is omnipresent in the plastic of common products such as beverage bottles, cans or baby bottles.

'Contaminants' Detected in Narragansett Watershed
Researchers say 'Emerging contaminants of concern' have been detected throughout the Narragansett Bay watershed.

New Plastics for Baby Bottles, Shopping Bags, More
With most of the plastics that define modern life dating to the1930s-1960s, a new breed of these ubiquitous materials are starting to gain a foothold.

September 21, 2011--------News Archive

Epigenetic Changes Don't Always Last
The first comprehensive inventory of epigenetic changes over several generations, shows that these changes often do not last.

Vacuum Device Makes Cellular Exploration Easier
New floating microscopic device will allow researchers to study a wide range of cellular processes.

September 20, 2011--------News Archive

11 Genetic Regions Link Schizophrenia/Bipolar Risk
Common genetic variants contribute to the risk of schizophrenia and bipolar disorder, an international research consortium has discovered.

Pediatric Brain Tumors
Regulatory protein presents potential drug target.

Crosstalk Between Bone, Fat and Pancreatic Cells
Cells in bone, fat and the pancreas appear to be talking to each other and one thing they likely are saying is, "Get moving."

September 19, 2011--------News Archive

Gene Catastrophe Causes Developmental Delay
Research has identified some cases of developmental delay or cognitive disorders associated with a sudden chromosomal catastrophe early in development.

Mom's High-Fat Diet 'Programs' Her Baby to Be Fat
This is the first study to demonstrate that a long-term maternal high-fat diet results in the deposition, in utero, of excess body fat in the newborn.

Length of Song Linked to Size of Bird's Upper Brain
Research has proven that the capacity for learning in birds is not linked to overall brain size, but to the relative size and proportion of their specific brain regions.

WHO Child Growth Charts


In an Arabidopsis plant, changes in the epigenetic code, from C to mC, can occur spontaneously.

Jean-Baptiste Lamarck would have been delighted: geneticists no longer dismiss out of hand his belief that acquired traits can be passed on to offspring.

When Darwin published his book on evolution, Lamarck's theory of transformation went onto the ash heap of history. But in the last decade, we have learned that the environment can after all leave traces in the genomes of animals and plants, in form of so-called epigenetic modifications. Scientists at the Max Planck Institute of Developmental Biology in Germany have now produced the first comprehensive inventory of spontaneous epigenetic changes.

Using Arabidopsis, the workhorse of modern plant genetics, the researchers determined how often and where in the genome epigenetic modifications occur – and how often they disappear again. They found that epigenetic changes are many orders of magnitude more frequent than conventional DNA mutations, but also often short lived. They are therefore probably much less important for long-term evolution than previously thought.

The team around Detlef Weigel, director of the Department for Molecular Biology, focused on one of the most important epigenetic marks, methylation of DNA. Tiny chemical building blocks, methyl groups, are thereby attached to individual letters of the DNA, mostly to cytosines.

The genetic information itself in form of the four different letters or nucleotides that make up the genetic code remains unchanged in this process.

To determine the rate and distribution of methylation changes in the genome, the German biologists looked at ten Arabidopsis lines. These lines came from the same stock, but had been propagated independently for 30 generations by self-fertilization. In the genome of the last generation the scientists then searched for differences in the methylation pattern in comparison to the common ancestor. They produced for each individual a complete map of methylated cytosines in the genome, the so-called methylome.

Epigenetic variations between the generations: The third generation of lines 4 and 8 serve as reference for the comparison of 10 lines after more than 30 generations.

"For each line, we were able to look at about 14 million cytosines," said Claude Becker, a member of the Tübingen team. On average, every plant had almost 3 million methylated cytosines.

The vast majority of these were the same in all lines, but about 6 percent had changed since the lines had become separated. At these positions, at least one of the individuals was different, with either methylation gained or lost relative to the ancestor. Each of the lines had about 30,000 such epimutations, which was 1,000 times more than DNA mutations.

With 30,000 epimutations after 30 generations, the geneticists had expected that 1,000 epimutations occurred in each generation. When they directly compared parents and their immediate offspring, they were surprised to find that the epimutation rate was three to four times as high.

The scientists concluded that many epimutations are apparently not stable and return to their original state after a few generations. Thus, averaging the mutation rate over many generations is misleading. Becker's colleague Jörg Hagmann therefore cautions not to overestimate the importance of DNA methylation during evolution:

"Our experiments show that methylation changes are often reversible". In other words: New epimutations are often not maintained over the long term. "Only when selection wins out over reversion can these epimutations affect evolution," says Hagmann.

A new epimutation must have a strong evolutionary advantage so that it can become established before being lost again. Because reverse mutations do not necessarily happen in the next generation, it is still possible that epigenetic differences contribute to inheritance of traits between parents and their children or grandparents and their grandchildren.

Another difference to ordinary mutations is that epimutations do not occur randomly, but often at the same places in the genome.

While genes were disproportionately affected, methylation of mobile DNA elements - transposons - was very stable. This appears to make sense, since it was already known that artificially induced loss of methylation has a much greater effect on the activity of transposons (sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell) than of regular genes.

Special enzymes transfer methyl groups to the cytosine building blocks of DNA. A methyl group consists of one carbon atom combined with three associated atoms of hydrogen (CH3).

Image Credits: Environmental Health Perspectives, 2006

More important than the state of individual cytosines is probably the methylation of larger segments of the genome.

"In each plant we found only about 30 such regions in which they differed from the other lines," explains Becker. Hagmann adds: "Such whole-sale epigenetic changes appear to be as rare as true DNA sequence mutations".

Still, these differences can appear very rapidly. The biologists discovered one region that first lost its methyl groups, only to become completely remethylated in the next generation.

What makes epigenetics interesting for human health is the fact that some epigenetic changes can be triggered by external factors.

There is evidence that nutrition, or the bond between children and their parents, can leave traces in the genome that can be passed on to the next generation.

However, the limited stability of DNA methylation implies that such differences do not necessarily last forever, which is probably not a bad idea as a famine might not last forever. It also means that altered DNA methylation often cannot become subject to natural selection.

The results of the Max Planck scientists demonstrate epigenetic differences can also arise spontaneously, without drastic changes in the environment. After all, the growth conditions in the green house, where each of the 10 lines was propagated, were constant. This opens the door to further speculation.

"We suspect that the epimutation increase is higher and more variable when plants grow in nature, where they are stressed all the time", says Becker.

If this were paralleled by an even higher reversion rate, then the importance of epigenetics for long-term evolution would be even lower.

Detlef Weigel, Claude Becker, Jörg Hagmann, Jonas Müller and Daniel Koenig in the Department of Molecular Biology at the Max Planck Institute for Developmental Biology, Germany; Oliver Stegle and Karsten Borgwardt from the Machine Learning and Computational Biology Research Group at the Max Planck Institutes for Developmental Biology and Intelligent Systems, Germany.

Original publication appears in Nature, September 20,2011
Claude Becker, Jörg Hagmann, Jonas Müller, Daniel Koenig, Oliver Stegle, Karsten Borgwardt and Detlef Weigel
Spontaneous epigenetic variation in the Arabidopsis thaliana methylome

Original article:
http://www.mpg.de/4426136/spontaneous_epigenetic_variation?filter_order=L