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!




Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

Contact The Visible Embryo

News 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

October 30, 2012--------News Archive Return to: News Alerts

“Your physiology and metabolism are very different when you sleep than during
the day or after you eat. The body constantly adjusts, and the central clock
regulates this adjustment. RORs play a major role in everyday human life.”

Anton Jetten, Ph.D.

WHO Child Growth Charts


Mediating the Body’s Clock and Metabolism

Over the past several years, researchers have discovered that disturbances to a person’s natural 24-hour wake-sleep cycle impact the body’s metabolism, and increase the risk of developing some cancers, diabetes, and obesity. Scientists have also found several nuclear receptors that play a role in this control. Now, a new study provides more details on how everything fits together

According to Anton Jetten, Ph.D., head of the National Institutes Environmental Health Sciences (NIEHS) Laboratory of Respiratory Biology, obesity is an important risk factor for developing insulin resistance and type 2 diabetes. His team found that mice, which lack the genes for retinoic acid-related orphan receptor (ROR) alpha or ROR gamma, remain sensitive to insulin and are much less susceptible to type 2 diabetes.

“Your physiology and metabolism are very different
when you sleep than during the day or after you eat.
The body constantly adjusts, and a central clock
regulates this adjustment.

RORs play a major role in everyday human life.”

Anton Jetten Ph.D.
head, NIEHS Laboratory of Respiratory Biology

Jetten's work also demonstrated how ROR receptors are involved in regulating clock and metabolic genes in 24-hour intervals. Part of this research appeared online June 29 in Nucleic Acids Research and reveals, for the first time, that ROR gamma, rather than ROR alpha, is the primary mediator between the body’s clock and its regulation of metabolic genes.

Jetten and others have shown that RORs are not only targets for environmental chemicals and hormones, but also regulate an organism’s circadian rhythms, or the physiological changes that occur in response to light and darkness – as explained in the National Institutes of General Medical Sciences (NIGMS) Circadian Rhythms Fact Sheet.

Jetten knows these interactions are complex, but finds them easier to understand if a person imagines himself or herself as ROR gamma. “When the alarm clock at home goes off in the morning, it tells your ROR gamma — to wake up and become active,” Jetten explained. “As you start doing things around the house, like taking a shower or getting food out of the refrigerator, these actions are initiated like the metabolic genes that ROR gamma acts upon.”

RORs are key to the connection

Yukimasa Takeda, Ph.D., Japanese Society for the Promotion of Science Research Fellow in Biomedical and Behavioral Research at NIH, joined Jetten’s group, because he was interested in this interplay.

He used knockout mice — ROR alpha, ROR gamma, and double knockouts — to tease out the association. To measure the mice’s circadian rhythms, Takeda collected tissue from several mice every 4-6 hours, and then analyzed changes in gene expression over a 24-hour period.

“Using microarray analysis, we were able to identify a number of metabolic genes, but we didn’t know whether they were direct or indirect targets of RORs,” Takeda said.

That’s when Jetten turned to ChIP-Seq, a powerful high-throughput method to map protein-DNA binding sites on a genome-wide scale. He submitted samples from the two knockout mice generating an enormous amount of genomic data.

At this point, Jetten needed the bioinformatics expertise of NIEHS colleague Raja Jothi, Ph.D., who accepted the challenge of analyzing the information. Although most of the data produced by Jothi through ChIP-Seq weren’t included in this paper, he and Jetten are working on another manuscript that examines new genes they have found.

After the analysis was complete, ChIP-Seq determined
that ROR gamma bound to the regulatory region
of several clock and metabolic genes,
while ROR alpha either displayed
much weaker binding or no binding at all.

The results confirmed these clock and metabolic genes
were directly regulated by RORs, and that ROR gamma
was more important in this regulation than ROR alpha.

Prior to this work, many in the nuclear receptor
community believed that ROR alpha
was more important.

Jetten adds that although he and his team know disturbances in the circadian clock can promote obesity and diabetes - and that loss of ROR gamma can inhibit this susceptibility, understanding the exact mechanism of how ROR gamma does its job needs further study.

“For a scientist,” Jetten continued, “that’s what drives you — finding out how things work.”

Citation: Takeda Y, Jothi R, Birault V, Jetten AM. (http://www.ncbi.nlm.nih.gov/pubmed/22753030) 2012. ROR gamma directly regulates the circadian expression of clock genes and downstream targets in vivo. Nucleic Acids Res; doi:10.1093/nar/gks630 [Online 29 June 2012].

Original article: http://www.niehs.nih.gov/news/newsletter/2012/8/science-mediating/index.htm