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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 25, 2013

 

Above: Prostate gland adenocarcinoma

In 2006, a group of researchers first reported the presence of very small embryonic-like stem cells,
or VSELs, in mice. Subsequent studies provided evidence that VESLs also exist in human blood
and bone marrow and could turn into specialized cells such as lung cells. But  Irving Weissman, Director of the Stanford Institute of Stem Cell Biology and Regenerative Medicine cannot replicate
the initial research or find evidence that VSELs are more than cell debris.





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Clinical value of very small embryonic-like stem cells?

Scientists have reported that very small embryonic-like stem cells (VSELs), which can be isolated from blood or bone marrow rather than embryos, could represent an alternative to mouse and human embryonic stem cells for research and medicine. But their very existence is hotly debated.

A study appearing online on July 24th in the ISSCR's journal Stem Cell Reports, published by Cell Press, provides strong evidence against the existence of VSELs capable of turning into different cell types. The findings call into question current plans to launch a clinical trial aimed at testing whether VSELs can be used for regenerative medicine in humans.


"To know when a stem cell discovery is true, it must meet several criteria. First, the work must be published in a peer-reviewed journal; second, other labs in the field should be able to repeat the findings; third, the phenomenon should be so robust that other experimental methods must reveal it; and fourth, in the stem cell field, the regeneration that occurs must be rapid, robust, and lifelong. In our study, we did not find evidence supporting the second, third, and fourth requirements."

Irving Weissman, senior study author, Stanford University School of Medicine


In 2006, a group of researchers first reported the presence of VSELs in mice. Subsequent studies have provided evidence that these cells also exist in human blood and bone marrow and could turn into specialized cells such as lung cells, a finding which may be useful for replacing damaged tissue. But other labs have failed to replicate these findings.

Nonetheless, a biopharmaceutical company called Neostem, which acquired the exclusive license to VSEL technology, plans to apply for Food and Drug Administration approval to carry out a first-in-man trial to test whether VSELs can regenerate bone.

In light of these conflicting results, Weissman and his team made the most rigorous effort yet to replicate the original VSEL findings. Although they used a variety of protocols, they failed to find VSELs derived from mouse bone marrow that could turn into specialized blood cells. Instead, the "VSELs" appeared to be artifacts such as cell debris and fragments from dying cells.

"Our findings clearly refute the basis in mouse studies that VSELs have the potentials claimed, and therefore call into question claims that these cells have potential for clinical application in humans," Weissman says.

Another article that will be published on the same day in the journal Cell Stem Cell reviews the controversy surrounding VSELs and includes wide-ranging commentary from experts in the field.

Summary
Very small embryonic-like stem cells (VSELs) isolated from bone marrow (BM) have been reported to be pluripotent. Given their nonembryonic source, they could replace blastocyst-derived embryonic stem cells in research and medicine. However, their multiple-germ-layer potential has been incompletely studied. Here, we show that we cannot find VSELs in mouse BM with any of the reported stem cell potentials, specifically for hematopoiesis. We found that: (1) most events within the “VSEL” flow-cytometry gate had little DNA and the cells corresponding to these events (2) could not form spheres, (3) did not express Oct4, and (4) could not differentiate into blood cells. These results provide a failure to confirm the existence of pluripotent VSELs.

Stem Cell Reports, Miyanishi et al.: "Do pluripotent stem cells exist in adult mice as very small embryonic stem cells?"

Original press release: http://www.eurekalert.org/pub_releases/2013-07/cp-nsr071813.php