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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.

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!




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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 Jan 30, 2014

Drosophila melanogaster is a species of fly or Drosophilidae. The species is known
generally as the common fruit fly or vinegar fly. Here they are on an overripe cherry.
Image credit: Anna Schroll



(see also our press release "A Direct Line through the Brain to Avoid Rotten Food - A Full STOP Signal for Drosophila ? Odor activation of a dedicated neural pathway by geosmin, an odor produced by toxic microorganisms, activates a hard-wired avoidance response in the fly": http://www.ice.mpg.de/ext/971.html, December 7, 2012)

Things smell good for a reason...

Fruit flies can smell healthy antioxidants in fruit and eating these antioxidants protects the fruit fly's cells from "free radicals." Humans also use smell to detect "healthy" food. But we are just beginning to understand how — and why.

Scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany, and the University of Lund, Sweden, have found that vinegar flies are able to detect protective antioxidants by using smell. Odors exclusively from antioxidants attract flies. This increases their interest in feeding and triggers females to lay their eggs. The research is published in Current Biology, January 2015.

Hydroxycinnamic acids are important dietary antioxidants. For animals including humans, anti-oxidants are an essential part of a healthy diet. They protect cells and boost our immune system. Notably, they prevent too many free radicals, mostly oxygen compounds, that create a  condition called oxidative stress.

If an organism suffers from oxidative stress, free radicals attack its cells and weaken its immune system. In fruit flies, oxidative stress is the result of an immune response to toxins produced by pathogens in food.

Hydroxycinnamic acids are found in high amounts in fruit — and fruit is the preferred breeding ground for fruit flies. So scientists in the Department of Evolutionary Neuroethology at the Max-Planck-Institute for Chemical Ecology in Jena, Germany, took a closer look at these acids and their attraction to fruit flies.

Although fruit flies cannot smell hydroxycinnamic acids, yeasts metabolize antioxidants and produce ethylphenols which flies can smell. Ethylphenols turn on a specific odor receptor located on mouth parts of fruit flies. Interestingly, this same odor receptor is also found in fly larvae. Smelling this odor increases feeding behavior in the fruit fly and even egg laying behavior in female fruit flies.

Marcus Stensmyr is the scientist who carried out the studies along with his colleagues. Stensmyr traced an individual neural pathway from the odor signal, to olfactory neurons and odor receptors, and then observed its resulting behavior in the fruit flies. This pathway is the olfactory detector for dietary antioxidants. Tracing it revealed a facet of the complex odor-guided behavior within fruit flies. Now scientists will try to identify further neural pathways for detecting other essential nutrients and their ultimate trigger affects on fly behavior.

"This form of olfactory detection is not only a phenomenon in insects. It has also been shown in humans. Odors that we perceive as pleasant or appetizing, are in fact derived from important and healthy nutrients, such as essential amino acids, fatty acids and vitamins."

Marcus Stensmyr PhD, Department of Evolutionary Neuroethology, senior lecturer University of Lund.

•Flies prefer the smell of yeast grown on media enriched with dietary antioxidants
•Attraction is due to yeast-produced ethylphenols derived from the antioxidants
•The ethylphenols are detected by maxillary palp neurons expressing Or71a
•Larvae are also attracted to the same ethylphenols but rely on a different receptor

Dietary antioxidants play an important role in preventing oxidative stress. Whether animals in search of food or brood sites are able to judge the antioxidant content, and if so actively seek out resources with enriched antioxidant content, remains unclear.

We show here that the vinegar fly Drosophila melanogaster detects the presence of hydroxycinnamic acids (HCAs)—potent dietary antioxidants abundant in fruit—via olfactory cues. Flies are unable to smell HCAs directly but are equipped with dedicated olfactory sensory neurons detecting yeast-produced ethylphenols that are exclusively derived from HCAs. These neurons are housed on the maxillary palps, express the odorant receptor Or71a, and are necessary and sufficient for proxy detection of HCAs. Activation of these neurons in adult flies induces positive chemotaxis, oviposition, and increased feeding. We further demonstrate that fly larvae also seek out yeast enriched with HCAs and that larvae use the same ethylphenol cues as the adults but rely for detection upon a larval unique odorant receptor (Or94b), which is co-expressed with a receptor (Or94a) detecting a general yeast volatile. We also show that the ethylphenols act as reliable cues for the presence of dietary antioxidants, as these volatiles are produced—upon supplementation of HCAs—by a wide range of yeasts known to be consumed by flies.

For flies, dietary antioxidants are presumably important to counteract acute oxidative stress induced by consumption or by infection by entomopathogenic microorganisms. The ethylphenol pathway described here adds another layer to the fly’s defensive arsenal against toxic microbes.

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