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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 July 16, 2013

 

Myc im mouse embryo

Left: An early mouse embryo in which the scientists generated a genetic
mosaic of two cell populations, green and blue.

Center: Three days later, the green cells, in which the levels of Myc protein have been
artificially increased, have won the battle and eliminated the blue cells.

Right: A cell with more Myc (green) engulfing one of its neighbors.





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Cells in the early embryo compete to become part of the whole

Researchers have found that during the early stages of mammalian development, embryonic cells battle for survival. Through this struggle, less active cells are eliminated by their stronger sisters.

The work is published today in the prestigious journal Nature.

This phenomenon, termed cell competition, occurs in a defined time window, between days 3 and 7 of mouse development. During this period all embryonic cells compete with each other, as explained by Dr. Cristina Claveria, first author of the study, and Dr. Miguel Torres, director of this work and Head of the Department of Cardiovascular Development and Repair at CNIC.


"Thanks to cell competition the developing organism optimizes itself by selecting the cells theoretically more capable of supporting vital functions throughout the life of the new individual," says Dr. Claveria.

According to the authors, this would be particularly important in long-lived organisms, like humans, where the functionality of their tissues must be maintained throughout a long life.


Dr. Miguel Torres also explains that when cell competition is prevented, cells that normally would have lost the battle now become able to contribute to the new organism: "We think, however, that this organism will probably be less capable than the one which would have been formed under normal circumstances. In what sense will it be less adequate is a matter of great interest that we will address in the coming years.”

Indeed, the researchers are able to determine in advance which cells will win this battle: those with higher levels of the Myc protein, an important controller of cell metabolic capacity. Moreover, using a new technique that they have developed for the production of genetic mosaics, they are able to manipulate the levels of Myc protein in cells, thus changing the outcome of the fight.


According to Claveria and Torres, the study shows that the early embryo is a mosaic of cells with very different levels of Myc, in which cells with higher levels of Myc eliminate those with lower levels.

However, it is important to understand that those who die are viable cells. "Their removal occurs only because the embryo has more suitable cells able to replace them, and therefore this is an optimization mechanism, not a repair one," the researchers point out.


A fascinating aspect of the work is the illustration that this battle does not waste cellular resources; dying loser cells are engulfed and digested by their winning neighbours, who then recycle and use all the nutrients for the benefit of the embryo.

This research provides answers to some of the questions raised nearly forty years ago by Spanish scientists Ginés Morata and Pedro Ripoll, who in 1975 discovered cell competition in the fruit fly.

On that occasion they described the phenomenon in the fly’s wing. Since then cell competition has been suggested to be involved in multiple processes, including tumour progression and tissue regeneration; but never, until this study, had a natural function been described.

Original press release: http://www.cnic.es/en/noticias/index.php?id=3793