Welcome to The Visible Embryo



Home-- -History-- -Bibliography- -Pregnancy Timeline- --Prescription Drugs in Pregnancy- -- Pregnancy Calculator- --Female Reproductive System- -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 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.

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!




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.


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
Google Search artcles published since 2007

Home | Pregnancy Timeline | News Alerts |News Archive May 15, 2014


This heart tissue was grown in a dish from mouse cardiac progenitor cells (CPCs).
The CPCs, and the tissue they built, were engineered to produce a red protein.
Click here to see the movie of the heart cells pulsing gently in the dish.


WHO Child Growth Charts




Potentially powerful tool for treating damaged hearts

A type of cell that builds mouse hearts can renew itself and may also lead to new insights into congenital heart defects.

A type of cell that builds mouse hearts can renew itself, Johns Hopkins researchers report. Their discovery, which likely applies to human cells as well, may pave the way to using them to repair hearts damaged by disease — or even grow new heart tissue for transplantation.

In a study published in the journal eLife, the scientists also revealed that during heart formation, these so-called cardiac progenitor cells (CPCs) multiply without becoming heart cells in the environment known as the second pharyngeal arch of the heart. This insight into the biology of CPCs may contribute to better understanding of how to prevent and treat congenital heart defects, they believe.

"Our finding that CPCs are self-renewing — that they can keep dividing to form new CPCs — means they might eventually be maintained in a dish and used to make specific types of heart cells. Growing such cells in a dish would be an enormous step toward better treatment for heart disease."

Chulan Kwon, PhD, assistant professor of cardiology, member of the Institute for Cell Engineering, Johns Hopkins University School of Medicine.

Kwon's research group's first step was figuring out the role of two genes, Numb and Numbl, in CPCs, which others' studies had shown are needed for guiding stem and progenitor cells to their fully mature, specialized functions. Numb and Numbl are highly conserved, meaning that they're nearly identical in mice, humans and other animals, and have been conserved over time and passed on through many life forms, a sign that these genes are likely very important.

To find out whether these genes are required for heart formation, the group disabled the Numb and Numbl genes in early CPCs of mouse embryos.

"The embryos failed to develop normal hearts and died at an early stage of development, showing us that Numb and Numbl are needed for CPCs to build the heart."

Chulan Kwon, PhD

The researchers next set out to find where CPCs exist in the developing embryo. Using mouse embryonic stem cells, they again disabled Numb and Numbl, also engineering the cells to produce a glowing red protein to indicate the CPCs' location. But because the engineered stem cells alone won't grow into a viable embryo, the team injected them into normal mouse blastocysts — the structure that forms both the embryo and placenta. "The normal cells in these blastocysts compensated for those that lacked Numb and Numbl, allowing the resulting embryos to survive," Kwon says.

When the team checked the hearts of the embryos, they found the glowing red cells in the second pharyngeal arch, which gives rise to the neck and face. Kwon says theirs is the first study to identify the second pharyngeal arch as home to CPCs. Taking cells surrounding the CPCs from this arch, the team then grew them in a dish and found that the CPCs self-renewed without developing into specialized heart cells — an important step toward using CPCs to treat heart disease.

The next step, Kwon says, is to coax the lab-grown CPCs into tissue to regenerate disease-damaged hearts. "Eventually, we might even be able to deliver cells to damaged hearts to repair heart disease," Kwon says.

Cardiac progenitor cells (CPCs) must control their number and fate to sustain the rapid heart growth during development, yet the intrinsic factors and environment governing these processes remain unclear. Here, we show that deletion of the ancient cell-fate regulator Numb (Nb) and its homologue Numblike (Nbl) depletes CPCs in second pharyngeal arches (PA2s) and is associated with an atrophic heart. With histological, flow cytometric and functional analyses, we find that CPCs remain undifferentiated and expansive in the PA2, but differentiate into cardiac cells as they exit the arch. Tracing of Nb- and Nbl-deficient CPCs by lineage-specific mosaicism reveals that the CPCs normally populate in the PA2, but lose their expansion potential in the PA2. These findings demonstrate that Nb and Nbl are intrinsic factors crucial for the renewal of CPCs in the PA2 and that the PA2 serves as a microenvironment for their expansion

Link to the article:http://elifesciences.org/content/early/2014/04/23/eLife.02164
Other authors on the paper were Lincoln Shenje, Peter Andersen, Hideki Uosaki, Laviel Fernandez, Peter Rainer, Gunsik Cho, Dong-ik Lee and David Kass of The Johns Hopkins University; Weimin Zhong of Yale University; and Richard Harvey of the Victor Chang Cardiac Research Institute.

Return to top of page