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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.

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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!




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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


Chromosome errors may explain brain birth defects

Balanced Chromosomal Abnormalities — or BCAs — are structural changes to the human genome. They may account for a large portion of birth defects affecting how our brain develops and functions.

New findings were just presented at the American Society of Human Genetics (ASHG) 2015 Annual Meeting in Baltimore, MD.

BCAs are changes to the structure of a chromosome where one or more fragments of DNA break apart and reattach elsewhere in the genome, either to the same chromosome or on a different one. In the simplest form, a single fragment moves to another region of the genome. But, BCA rearrangements can involve many fragments attaching to many chromosomes.

Unlike Chromosomal Deletions or Duplications, BCAs do not generate gain or loss of genetic material — they disrupt the function of DNA. Fragment attachment points create DNA breaks, first from their original location and then in their new location. These breaks are implicated in birth defects found in our developing neurologic system.

"We studied BCAs in 111 patients with congenital neurodevelopmental conditions and 36 patients with other conditions, mapping where their breakpoints appear. By mapping these breakpoints, we identified genes disrupted in patients with birth defects, suggesting these genes play a key role in normal brain development."

Claire Redin PhD, postdoctoral candidate, Massachusetts General Hospital and the Broad Institute, first author on the new study.

Because no genetic material is gained or lost, conventional gene analysis tests cannot easily detect BCAs — and therefore don't assign much importance to them as significant cause for alarm. But Dr. Redin and her colleagues used a modified version of whole-genome sequencing to locate large, overlapping strands of DNA, and found breakpoints.

When sequences normally located far apart in the genome were found on the same strand or adjacent strands, this arrangement confirmed a BCA had brought them together. Researchers then closely examined the gene to identify what had been disrupted at that breakpoint.

"As a first step, we looked at how the breakpoint locations mapped relative to known disease genes, to see how many of the defects we observed in patients could be explained by these disruptions," Dr. Redin said.

What they found out about BCA breakpoints:
46 percent of breakpoints disrupted a single gene
24 percent disrupted regions between genes
30 percent disrupted at least two genes.

The researchers also studied other genomic features near the breakpoints to see what may be triggering the DNA to break apart at any specific location. Unsurprisingly, they observed that breakpoints tend to coincide with known recombination 'hotspots' — specific regions where genetic exchange between a person's corresponding chromosomes occur.

They also identified genomic regions where BCAs seemed to cluster, including one narrow band in a region between genes, in which nine patients with similar neurodevelopmental conditions showed a breakpoint.

"There is obviously something unusual happening where BCAs cluster, which we plan to study in future work. Our eventual goal is to predict the effects of BCAs based on where they are located and which genes are disrupted."

Claire Redin PhD

Researchers are currently conducting a more detailed analysis of the 24 percent of breakpoints located between genes and how these may affect brain development.

Presentation: Dr. Redin presented her research on Saturday, October 10, 2015, from 9:35-9:55 a.m., in Hall F of the Baltimore Convention Center.

Press Availability: Dr. Redin will be available to discuss this research with interested media on Friday, October 9, 2015, from 11:00 a.m.-12:00 p.m., in the ASHG 2015 Press Office (Room 301).

Reference: Redin C et al. (2015 Oct 10). Abstract: Characterizing de novo balanced cytogenetic abnormalities through sequencing in 147 subjects with multiple congenital abnormalities. Presented at American Society of Human Genetics 2015 Annual Meeting. Baltimore, Md.

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Oct 14, 2015   Fetal Timeline   Maternal Timeline   News   News Archive   

Chromosome translocation occurs when a piece of one chromosome breaks off
and attaches to another chromosome. This type of rearrangement is described as
balanced if no genetic material is gained or lost in the cell. If there is a gain
or loss of genetic material, the translocation is described as unbalanced.
Image Credit: Lance genetics











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