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!



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 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 June 27, 2013

 

The history of life on earth goes back at least 3,850 million years

In 1948, P. E. Cloud argued that a period of
"eruptive" evolution occurred in the Early Cambrian.

But as recently as the 1970s there was no sign of how the relatively
modern-looking organisms of the Middle and Late Cambrian arose.

Other analyses, some recent and some dating back to the 1970s,
argue that complex animals similar to modern types
evolved well before the start of the Cambrian.






WHO Child Growth Charts

 

 

 

2 mutations trigger evolution leap 500 million years ago

Resurrecting ancient proteins in the lab, researchers discover just 2 mutations set the stage for the evolution of modern hormone signaling.

Evolution, it seems, sometimes jumps instead of crawls. A research team led by a University of Chicago scientist has discovered two key mutations that sparked a hormonal revolution 500 million years ago.

In a feat of "molecular time travel," the researchers resurrected and analyzed the functions of the ancestors of genes that play key roles in modern human reproduction, development, immunity and cancer. By re-creating the same DNA changes that occurred during those genes' ancient history, the team showed that two mutations set the stage for hormones like estrogen, testosterone and cortisol to take on their crucial present-day roles.


"Changes in just two letters of the genetic code in our deep evolutionary past caused a massive shift in the function of one protein and set in motion the evolution of our present-day hormonal and reproductive systems.

If those two mutations had not happened, our bodies today would have to use different mechanisms to regulate pregnancy, libido, the response to stress, kidney function, inflammation, and the development of male and female characteristics at puberty."

Joe Thornton, PhD, professor, Human Genetics, Ecology & Evolution, University of Chicago, study leader


The findings were published online June 24 in the Proceedings of the National Academy of Sciences.

Understanding how the genetic code of a protein determines its functions would allow biochemists to better design drugs and predict the effects of mutations on disease.

Thornton explains that the discovery shows how evolutionary analysis of proteins' histories can advance this goal. Before the group's work, it was not previously known how the various steroid receptors in modern species distinguish estrogens from other hormones.


The team, which included researchers from the University of Oregon, Emory University and the Scripps Research Institute, studied the evolution of a family of proteins called steroid hormone receptors, which mediate the effects of hormones on reproduction, development and physiology. Without receptor proteins, these hormones cannot affect the body's cells.

Thornton's group traced how the ancestor of the entire receptor family—which recognized only estrogens—evolved into descendant proteins capable of recognizing other steroid hormones, such as testosterone, progesterone and the stress hormone cortisol.


To do so, the group used a gene "resurrection" strategy. They first inferred the genetic sequences of ancient receptor proteins, using computational methods to work their way back up the tree of life from a database of hundreds of present-day receptor sequences. They then biochemically synthesized these ancient DNA sequences and used molecular assays to determine the receptors' sensitivity to various hormones.

Thornton's team narrowed down the time range during which the capacity to recognize non-estrogen steroids evolved, to a period about 500 million years ago, before the dawn of vertebrate animals on Earth. They then identified the most important mutations that occurred during that interval by introducing them into the reconstructed ancestral proteins. By measuring how the mutations affected the receptor's structure and function, the team could re-create ancient molecular evolution in the laboratory.


They found that just two changes in the ancient receptor's gene sequence caused a 70,000-fold shift in preference away from estrogens toward other steroid hormones.

The researchers also used biophysical techniques to identify the precise atomic-level mechanisms by which the mutations affected the protein's functions.

Although only a few atoms in the protein were changed, this radically rewired the network of interactions between the receptor and the hormone, leading to a massive change in function.


"Our findings show that new molecular functions can evolve by sudden large leaps due to a few tiny changes in the genetic code," Thornton said. He pointed out that, along with the two key changes in the receptor, additional mutations, the precise effects of which are not yet known, were necessary for the full effects of hormone signaling on the body to evolve.

This work was supported by grants from the National Institutes of Health, National Science Foundation and the Howard Hughes Medical Institute.

Original press release:http://www.uchospitals.edu/news/2013/20130624-mutations.html