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

 

To exert control, genetic information encoded by DNA must first be copied ,
or transcribed, into messenger RNA (mRNA).

When the DNA double helix unwinds revealing its genetic messages,
RNA transcription can proceed along it in either direction.

To initiate copying, an enzyme—called RNA polymerase—latches on
to the DNA at a spot known as the promoter. The RNA polymerase
then moves along the strand, building an mRNA chain as it goes.

When the RNA polymerase reaches a stop signal at the end of a gene ,
it halts transcription and adds bases—known as a poly-A tail—to
the mRNA sequence, consisting of a long string of the base adenine.

This process, known as polyadenylation, helps prepare the mRNA
molecule to be exported from the cell’s nucleus.








WHO Child Growth Charts

 

 

 

Reading DNA, backward and forward

MIT biologists reveal how cells control the direction in which the genome is read.

by Anne Trafton, MIT News Office

MIT biologists have discovered a mechanism that allows cells to read their own DNA in the correct direction and prevents them from copying most of the so-called “junk DNA” that makes up long stretches of our genome.


Only about 15 percent of the human genome consists of protein-coding genes, but in recent years scientists have found that a surprising amount of the junk, or intergenic DNA, does get copied into RNA — the molecule that carries DNA’s messages to the rest of the cell.


Scientists have been trying to figure out just what this RNA might be doing, if anything. In 2008, MIT researchers led by Institute Professor Phillip Sharp discovered that much of this RNA is generated through a process called divergent expression, through which cells read their DNA in both directions moving away from a given starting point.


In a new paper appearing in Nature on June 23, Sharp and colleagues describe how cells initiate but then halt the copying of RNA in the upstream, or non-protein-coding direction, while allowing it to continue in the direction in which genes are correctly read.

This finding helps explain the existence of many recently discovered types of short strands of RNA whose function is unknown.


“This is part of an RNA revolution where we’re seeing different RNAs and new RNAs that we hadn’t suspected were present in cells, and trying to understand what role they have in the health of the cell or the viability of the cell,” says Sharp, who is a member of MIT’s Koch Institute for Integrative Cancer Research. “It gives us a whole new appreciation of the balance of the fundamental processes that allow cells to function.”

Graduate students Albert Almada and Xuebing Wu are the lead authors of the paper. Christopher Burge, a professor of biology and biological engineering, and undergraduate Andrea Kriz are also authors.

Choosing direction

DNA, which is housed within the nucleus of cells, controls cellular activity by coding for the production of RNAs and proteins.


To exert control, genetic information encoded by DNA must first be copied, or transcribed, into messenger RNA (mRNA).

When the DNA double helix unwinds to reveal its genetic messages, RNA transcription can proceed in either direction. To initiate this copying, an enzyme called RNA polymerase latches on to the DNA at a spot known as the promoter. The RNA polymerase then moves along the strand, building the mRNA chain as it goes.

When the RNA polymerase reaches a stop signal at the end of a gene, it halts transcription and adds to the mRNA a sequence of bases known as a poly-A tail, which consists of a long string of the genetic base adenine. This process, known as polyadenylation, helps to prepare the mRNA molecule to be exported from the cell’s nucleus.


By sequencing the mRNA transcripts of mouse embryo stem cells, researchers discovered that polyadenylation also plays a major role in halting the transcription of upstream, noncoding DNA sequences. They found that these regions have a high density of signal sequences for polyadenylation— which prompts enzymes to chop up the RNA before it gets very long. Stretches of DNA that code for genes have a low density of these signal sequences.

The researchers also found another factor that influences whether transcription is allowed to continue. It has been recently shown that when a cellular factor known as U1 snRNP binds to RNA, polyadenylation— the addition of a poly(A) tail to an RNA molecule creating a stretch of RNA with only adenine bases—is suppressed. The new MIT study found that genes have a higher concentration of binding sites for U1 snRNP than noncoding sequences, allowing gene transcription to continue uninterrupted.

A widespread phenomenon

The function of all of this upstream noncoding RNA is still a subject of much investigation. “That transcriptional process could produce an RNA that has some function, or it could be a product of the nature of the biochemical reaction. This will be debated for a long time,” Sharp says.

His lab is now exploring the relationship between this transcription process and the observation of large numbers of so-called long noncoding RNAs (lncRNAs). He plans to investigate the mechanisms that control the synthesis of such RNAs and try to determine their functions.

“Once you see some data like this, it raises many more questions to be investigated, which I’m hoping will lead us to deeper insights into how our cells carry out their normal functions and how they change in malignancy,” Sharp says.

The research was funded by the National Institutes of Health, the National Cancer Institute and the National Institute of General Medical Sciences.

Original press release: http://web.mit.edu/press/2013/reading-dna-backward-and-forward.html: