Welcome to The Visible Embryo

Home- - -History-- -Bibliography- -Pregnancy Timeline- --Prescription Drugs in Pregnancy- -- Pregnancy Calculator- --Female Reproductive System- News Alerts -Contact

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!



Home

History

Bibliography

Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

Contact The Visible Embryo

News Alerts Archive

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.
Content protected under a Creative Commons License.

No dirivative works may be made or used for commercial purposes.

Return To Top Of Page
Pregnancy Timeline by SemestersFemale Reproductive SystemFertilizationThe Appearance of SomitesFirst TrimesterSecond TrimesterThird TrimesterFetal 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 HemispheresEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterDevelopmental Timeline
Click weeks 0 - 40 and follow fetal growth
Search artcles published since 2007

July 13, 2012--------News Archive Return to: News Alerts


Human embryo formation at 12 weeks post ovulation


Cardiac development out of control:
Absence of the transcription factor Ajuba during
cardiac development in the zebra fish,
as is the case in the right-hand photo
due to genetic intervention,
disrupts development of the heart in the fish embryo.
In addition to an increased number of cardiac muscle cells (green)
with red-stained nuclei, the heart is additionally deformed during development.
© Max Planck Institute for Heart and Lung Research

WHO Child Growth Charts

       

Finished Heart Switches Stem Cells Offmouse

Transcription factor Ajuba regulates stem cell activity in the heart during embryonic development


It is not unusual for babies to be born
with congenital heart defects.
This is because the development of the heart
in the embryo is a process which is not
only extremely complex,
but also error-prone.


Scientists from the Max Planck Institute for Heart and Lung Research in Bad Nauheim have now identified a key molecule that plays a central role in regulating the function of stem cells in the heart. As a result, not only could congenital heart defects be avoided in future, but new ways of stimulating the regeneration of damaged hearts in adults may be opened up.

It's a long road from a cluster of cells to a finished heart. Cell division transforms what starts out as a collection of only a few cardiac stem cells into an ever-larger structure from which the various parts of the heart, such as ventricles, atria, valves and coronary vessels, develop.

This involves the stem and precursor cells undergoing a complex process which, in addition to tightly regulated cell division, also includes cell migration, differentiation and specialisation.


Once the heart is complete,
the stem cells are finally switched off.


Scientists from the Max Planck Institute for Heart and Lung Research in Bad Nauheim have now discovered how major parts of this development process are regulated. Their search initially focused on finding binding partners for transcription factor Isl1.

Isl1 is characteristic of a specific group of cardiac stem cells which are consequently also known as Isl1+ cells. During their search, the researchers came across Ajuba, a transcription factor from the group of LIM proteins. "We then took a closer a look at the interaction between these two molecules and came to the conclusion that Ajuba must be an important switch," says Gergana Dobreva, head of the "Origin of Cardiac Cell Lineages" Research Group at the Bad Nauheim-based Max Planck Institute.

Using an animal model, the scientists then investigated the effects of a defective switch on cardiac development. Embryonic development can be investigated particularly effectively in the zebrafish. The Bad Nauheim-based researchers therefore produced a genetically modified fish that lacked a functioning Ajuba protein.

Cardiac development in these fishes was in fact severely disrupted. In addition to deformation of the heart, caused by twisting of the cardiac axis, what particularly struck the researchers was a difference in size in comparison with control animals.


"In almost all the investigated fish
we observed a dramatic enlargement of the heart.

If Ajuba is absent,
there is clearly no other switch that finally silences
the Isl1-controlled part of cardiac development."

Gergana Dobreva


Further investigations revealed that the enlargement of the heart is in fact attributable to a greatly increased number of cardiac muscle cells. The reason for this was in turn that the number of Isl1+ cells, i.e. the cardiac muscle precursor cells, was distinctly raised right from an early phase of development.


Ajuba is a decisive factor in controlling stem cell activity.
It binds to Isl1 molecules,
thus blocking their stimulant effect.


The results from the study could have potential future applications. "Once we understand how cardiac development is regulated, we will also be more familiar with the causes of congenital heart defects and will consequently be able to consider therapeutic approaches," comments Dobreva.

Damaged adult hearts can also be repaired in this way: "One possibility would be to optimise the production of replacement cells from embryonic or artificially produced stem cells in the laboratory. Silencing Ajuba in these cells might enhance their development into functional cardiac muscle cells. Sufficient replacement cells for treating patients could be cultured in this way."

Another possibility is to stimulate stem cell activity by silencing Ajuba in the damaged heart and so cause the heart to regenerate itself. Further studies are now set to investigate how feasible this might be.

Hagen R. Witzel, Benno Jungblut, Chong Pyo Choe, J. Gage Crump, Thomas Braun, and Gergana Dobreva

The LIM Protein Ajuba Restricts the Second Heart Field Progenitor Pool by Regulating Isl1 Activity.

Developmental Cell (2012)

Original article: http://www.mpg.de/5897042/heart_stem_cells