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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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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


 

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Home | Pregnancy Timeline | News Alerts | News Archive June 17, 2013

 
Overview of biological circadian clock in humans.

Biological clock affects the daily rhythm of many physiological processes.
This diagram depicts the circadian patterns typical of someone who rises early in morning,
eats lunch around noon, and sleeps at night (10 p.m.).

Although circadian rhythms tend to be synchronized with cycles of light and dark, other factors
- such as ambient temperature, meal times, stress and exercise - can influence the timing as well.





WHO Child Growth Charts

 

 

 

Neurodegeneration gene keeps biological clock running

Scientists identify another gene important to morning wake-up call. The gene is involved in neurodegenerative disease,but also plays a critical role in the proper function of the circadian clock.

by Megan Fellman

In a study of the common fruit fly, researchers found the gene—Ataxin-2—keeps the clock responsible for sleeping and waking on a 24-hour rhythm. Without the gene, the rhythm of the fruit fly’s sleep-wake cycle is disturbed, making waking up on a regular schedule difficult for the fly.


The discovery is particularly interesting because mutations in the human Ataxin-2 gene are known to cause a rare disorder called spinocerebellar ataxia (SCA) and also contribute to amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease.

People with SCA suffer from sleep abnormalities before other symptoms of the disease appear.


This study linking the Ataxin-2 gene with abnormalities in the sleep-wake cycle could help pinpoint what is causing these neurodegenerative diseases as well as provide a deeper understanding of the human sleep-wake cycle.

The findings will be published May 17 in the journal Science. Ravi Allada, M.D., professor of neurobiology in the Weinberg College of Arts and Sciences, and Chunghun Lim, a postdoctoral fellow in his lab, are authors of the paper.

Period (per) is a well-studied gene in fruit flies that encodes a protein, called PER, which regulates circadian rhythm. Allada and Lim discovered that Ataxin-2 helps activate translation of PER RNA into PER protein, a key step in making the circadian clock run properly.

“It’s possible that Ataxin-2’s function as an activator of protein translation may be central to understanding how, when you mutate the gene and disrupt its function, it may be causing or contributing to diseases such as ALS or spinocerebellar ataxia,” Allada said.

The fruit fly Drosophila melanogaster is a model organism for scientists studying the sleep-wake cycle because the fly’s genes are highly conserved with the genes of humans.

“I like to say that flies sleep similarly to humans, except flies don’t use pillows,” said Allada, who also is associate director for Northwestern’s Center for Sleep and Circadian Biology. The biological timing mechanism for all animals comes from a common ancestor hundreds of millions of years ago.

Ataxin-2 is the second gene in a little more than two years that Northwestern researchers have identified as a core gear of the circadian clock, and the two genes play similar roles.

Allada, Lim and colleagues in 2011 reported their discovery of a gene, which they dubbed “twenty-four,” that plays a role in translating the PER protein, keeping the sleep-wake cycle on a 24-hour rhythm.

Allada and Lim wanted to better understand how twenty-four works, so they looked at proteins that associate with twenty-four. They found the twenty-four protein sticking to ATAXIN-2 and decided to investigate further. In their experiments, reported in Science, Allada and Lim discovered the Ataxin-2 and twenty-four genes appear to be partners in PER protein translation.

“We’ve really started to define a pathway that regulates the circadian clock and seems to be especially important in a specific group of neurons that governs the fly’s morning wake-up,” Allada said. “We saw that the molecular and behavioral consequences of losing Ataxin-2 are nearly the same as losing twenty-four.”

As is the case in a mutation of the twenty-four gene, when the Ataxin-2 gene is not present, very little PER protein is found in the circadian pacemaker neurons of the brain, and the fly’s sleep-wake rhythm is disturbed.

The National Institute of Neurological Disorders and Stroke and the Defense Advanced Research Projects Agency supported the research.

The paper is titled “ATAXIN-2 Activates PERIOD Translation to Sustain Circadian Rhythms in Drosophila.” Lim, the first author, now is an assistant professor at the School of Nano-Bioscience and Chemical Engineering, UNIST, Republic of Korea.

Original press release:http://www.northwestern.edu/newscenter/stories/2013/05/gene-involved-in-neurodegeneration-keeps-clock-running.html