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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 March 6, 2014

 

This is a slice of the visual cortex of an embryonic macaque monkey.

Image Credit: neurosciencenews.com.



Figure 1. Timeline of gyrification in human. Stages 1 and 2 are delineated by GW 31-32.

There is a progressive lack of conservation in cortical folding patterns toward the final stages of gyrification,
as minor developmental changes in gyri and sulci become increasingly specialized to species and,
ultimately, susceptible to local environmental and experiential variations.
3D reconstructions of fetal human brains from Barnette et al. (2009). Figure follows Sawada et al. (2012b).

See more at: http://journal.frontiersin.org/Journal/10.3389/fnhum.2013.00424/full#sthash.swDDBdn7.dpuf






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Evolution at work

A slice of brain from a macaque monkey embryo reveals unique evolutionary innovation in the primate brain.

New research by the University of California at Santa Barbara (UCSB) professor Kenneth S. Kosik, Harriman Professor of Neuroscience, is published in the journal Neuron. The research describes the role of microRNAs — so named because they contain only 22 nucleotides — in a portion of the brain called the outer subventricular zone (OSVZ). These microRNAs belong to a special category of noncoding genes that prevent the formation of proteins.


“MicroRNAs provide a wiring diagram, dictating which genes are turned on, when they’re turned on, and where they’re turned on.

“There appears to be a core set with which all kinds of really complex things can be built, and noncoding genes know how to pull it together.”

Kenneth S. Kosik, co-director, Neuroscience Research Institute, professor, Department of Molecular, Cellular and Developmental Biology, UCSB.


The researchers were looking for these noncoding genes, says Kosik, because as organisms become more complex through evolution, the number of these noncoding genes has greatly expanded. “But the coding genes — the ones that make proteins — have really not changed very much,” he adds. “The real action is in this noncoding area and what that part of the genome is doing is controlling the genes.”

Many of the microRNAs that Kosik’s team found and sequenced are newly evolved in primates. Kosik’s work shows that these tiny control elements are overrepresented in the OSVZ (outer subventricular zone) of developing macaque brains. The tissue samples were provided by a lab at the Stem-cell and Brain Research Institute near Lyon, France, headed by research director and co-author Colette Dehay.


Study results indicate that the appearance of the OSVZ is very much associated with the invention of new microRNAs.


“There might be some relationship — although we can’t prove it — between the invention of some of these new noncoding genes, microRNAs, and the appearance of the new structure, the OSVZ,” says Kosik. “Trying to connect an anatomical, morphological invention with genes is very difficult, but our work shows a possible molecular basis for the tools that were needed to build this novel structure.”

The analysis found that these new microRNAs target old genes, many involved in the cell cycle, which is responsible for cell division (mitosis).


“Nearly all cells throughout evolution have a cell cycle.

'We can now watch the evolutionary process at a molecular level and see what is novel and how molecular innovation affects what already exists — such as the cell cycle.

"When new things are invented through evolution, they have to be integrated with what already exists.
What I find fascinating is that the whole ancient mechanism of cell division still has enough evolutionary muscle to make something new — and to make something new that’s really complex.

“The OSVZ gave rise to primates’ expanded brains and to the cells that ultimately brought us Shakespeare.”

Kenneth S. Kosik, PhD


According to Kosik, the microRNAs he studied are a blend of molecular and anatomical information.

Kosik: “Some of the genes we identified are targets of these new microRNAs, and are also involved in certain human genetic developmental disorders.

“So we would like to explore the pathways that we might be able to manipulate to help patients. We know people with developmental disorders can be missing a critical gene involved in brain formation and wiring, so maybe if we understood the control of those genes — as this new data points to — we might be able to do something that could be applied to a human condition.”

Abstract
Major nonprimate-primate differences in corticogenesis include the dimensions, precursor lineages, and developmental timing of the germinal zones (GZs). microRNAs (miRNAs) of laser-dissected GZ compartments and cortical plate (CP) from embryonic E80 macaque visual cortex were deep sequenced. The CP and the GZ including ventricular zone (VZ) and outer and inner subcompartments of the outer subventricular zone (OSVZ) in area 17 displayed unique miRNA profiles. miRNAs present in primate, but absent in rodent, contributed disproportionately to the differential expression between GZ subregions. Prominent among the validated targets of these miRNAs were cell-cycle and neurogenesis regulators. Coevolution between the emergent miRNAs and their targets suggested that novel miRNAs became integrated into ancient gene circuitry to exert additional control over proliferation. We conclude that multiple cell-cycle regulatory events contribute to the emergence of primate-specific cortical features, including the OSVZ, generated enlarged supragranular layers, largely responsible for the increased primate cortex computational abilities.

See more at: http://www.news.ucsb.edu/2014/013971/study-reveals-evolution-work#sthash.oWHI0gvf.dpuf