Welcome to The Visible Embryo
The Visible Embryo Home
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 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 SemestersDevelopmental TimelineFertilizationFirst TrimesterSecond TrimesterThird TrimesterFirst Thin Layer of Skin AppearsEnd of Embryonic PeriodEnd of Embryonic PeriodFemale Reproductive SystemBeginning Cerebral HemispheresA Four Chambered HeartFirst Detectable Brain WavesThe Appearance of SomitesBasic Brain Structure in PlaceHeartbeat can be detectedHeartbeat can be detectedFinger and toe prints appearFinger and toe prints appearFetal sexual organs visibleBrown fat surrounds lymphatic systemBone marrow starts making blood cellsBone marrow starts making blood cellsInner Ear Bones HardenSensory brain waves begin to activateSensory brain waves begin to activateFetal liver is producing blood cellsBrain convolutions beginBrain convolutions beginImmune system beginningWhite fat begins to be madeHead may position into pelvisWhite fat begins to be madePeriod of rapid brain growthFull TermHead may position into pelvisImmune system beginningLungs begin to produce surfactant
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development


Fetal Timeline      Maternal Timeline      News     News Archive    Aug 20, 2015 

A new method significantly improves the ability of scientists to "edit"
faulty genes and replace damaged gene code with healthy DNA.
Image Credit:






Engineering a solution to genetic diseases

New study advances scientists' ability to permanently 'edit' faulty genes.

In his mind, Basil Hubbard can already picture a new world of therapeutic treatments for millions of patients just over the horizon. It's a future in which diseases like muscular dystrophy, cystic fibrosis and many others, are treated permanently through the science of genome engineering. Thanks to his latest work, Hubbard is bringing that future closer to reality.

Hubbard's research, published in the journal Nature Methods, demonstrates a new technology advancing the field of genome engineering. The method significantly improves the ability of scientists to target specific faulty genes, and then "edit" them, as in replace the damaged genetic code with healthy DNA.

"There is a trend in the scientific community to develop therapeutics in a more rational fashion, rather than just relying on traditional chemical screens. We're moving towards a very logical type of treatment for genetic diseases, where we can actually say, 'Your disease is caused by a mutation in gene X, and we're going to correct this mutation to treat it'.

"In theory, genome engineering will eventually allow us to permanently cure genetic diseases by editing the specific faulty gene(s)."

Basil Hubbard PhD, Assistant Professor of Pharmacology, University of Alberta's Faculty of Medicine & Dentistry, Alberta, Canada.

Genome engineering involves modification of an organism's specific genetic information. Just as a computer programmer edits computer code, the idea is that scientists could one day replace a person's broken or unhealthy genes with healthy ones using sequence-specific DNA binding proteins attached with DNA-editing tools. The field has made large strides in the last two decades and may revolutionize medical care.

One of the obstacles still to be addressed though, is how to ensure the proteins only affect the specific targeted genes in need of repair. With current technologies, the proteins bind and correctly edit genes the majority of the time, but more improvement is needed to insure potential errors never occur.

In the lab of David R. Liu at Harvard University, Hubbard has developed a way to reduce the possibility of off-target DNA binding with a class of gene editing proteins known as transcription activator-like effector nucleases or TALENs. His new method called DNA-binding phage-assisted continuous evolution or DB-PACE, allows researchers to rapidly evolve the TALEN proteins autonomously over time, in order to make them more specific to their gene target.

"This technology allows you to systematically say, 'I want to target this DNA sequence, and I don't want to target these others,' and it basically evolves a protein to do just that. Using this system, we can produce gene editing tools that are 100 times more specific for their target sequence."

Basil Hubbard PhD

Currently much of the research in the field of gene engineering is focused on treating monogenic diseases — or diseases of a single gene — as they're much easier to target. Diseases such as hemophilia, sickle cell anemia, muscular dystrophy and cystic fibrosis are monogenic.

While the field is still in its infancy, Hubbard says human clinical trials are already underway. If successful, he expects the first clinical applications could be in use in the next decade.

"Whereas traditional pharmaceutical drugs have a transient effect, gene editing could possibly provide a permanent cure for a lot of different diseases. We still have to overcome many hurdles but I think this technology definitely has the potential to be transformative in medicine."

Basil Hubbard PhD

Nucleases containing programmable DNA-binding domains can alter the genomes of model organisms and have the potential to become human therapeutics. Here we present DNA-binding phage-assisted continuous evolution (DB-PACE) as a general approach for the laboratory evolution of DNA-binding activity and specificity. We used this system to generate transcription activator–like effectors nucleases (TALENs) with broadly improved DNA cleavage specificity, establishing DB-PACE as a versatile approach for improving the accuracy of genome-editing agents.

Research funding was provided by the U.S. Defense Advanced Research Projects Agency (DARPA).

Return to top of page