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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 Dec 13, 2013

 

A side-by-side comparison of a normal zebrafish embryo and a zebrafish embryo
lacking the enzyme acyl-CoA synthetase or ACSL4.

Image Credit to RosaLinda Miyares.







WHO Child Growth Charts

 

 

 

Fatty acids are crucial to embryo development

One classic question in developmental biology is how different tissue types grow correctly positioned in the embryo. Unexpected findings reveal the importance of polyunsaturated fatty acids in this process.

Fatty acids serve as sources of energy, the building materials of cell membranes, and for signals sending messages between cells. Enzymes activate free fatty acids so that they are made available for cell processes. These enzymes are called acyl-CoA synthetases, often shortened to ACS.


One member of the ACS family, ACSL4, activates special fatty acids called polyunsaturated fatty acids.

Mutations in ACSL4 are linked to human developmental disorders including a type of mental retardation that is linked to the X chromosome.

Mammalian and fruit fly ACSL4 enzymes have shown to play roles in brain development and embryonic survival.


However, researching roles for mammalian ACSL4 in embryonic development has been confounded by the maternal delivery of polyunsaturated fatty acids to the developing embryo, as well as the need for polyunsaturated fatty acids in embryo implantation and uterus development.

Carnegie Institution's Steven Farber and his team, including lead author Rosa Miyares, collaborated with the Hammerschmidt lab at the University of Cologne Germany utilized the externally developing zebrafish to understand what ACSL4 does during embryogenesis.


Rosa Miyares and her team demonstrated that ACSL4 is essential for embryos to develop proper tissue organization.

They show that ACSL4 enzyme activity regulates a specific protein in the Bmp signaling pathway, essential for proper embryo organization.


"We've known for some time that polyunsaturated fatty acids are important to prenatal health; in the US, these fatty acids are widely included in prenatal vitamins.

"By connecting polyunsaturated fatty acid metabolism with a fundamental signaling pathway in the early embryo, our study provides a clue as to why they are so critical. These results lay the groundwork for further research on polyunsaturated fatty acid metabolism and its various roles in development and disease."
  adds Steven Farber.

Published online December 12 in Developmental Cell.

Abstract
Highlights
PUFA-modifying enzyme Acsl4a is essential for zebrafish dorsoventral patterning
Acsl4a enhances Bmp signaling via stabilization of Bmp-Smad transcription factors
Acsl4a loss activates p38 and GSK3, resulting in Smad phosphorylation and degradation
Ascl4a inhibits GSK3 via activation of AKT
Summary

Long-chain polyunsaturated fatty acids (LC-PUFA) and their metabolites are critical players in cell biology and embryonic development. Here we show that long-chain acyl-CoA synthetase 4a (Acsl4a), an LC-PUFA activating enzyme, is essential for proper patterning of the zebrafish dorsoventral axis. Loss of Acsl4a results in dorsalized embryos due to attenuated bone morphogenetic protein (Bmp) signaling. We demonstrate that Acsl4a modulates the activity of Smad transcription factors, the downstream mediators of Bmp signaling. Acsl4a promotes the inhibition of p38 mitogen-activated protein kinase and the Akt-mediated inhibition of glycogen synthase kinase 3, critical inhibitors of Smad activity. Consequently, introduction of a constitutively active Akt can rescue the dorsalized phenotype of Acsl4a-deficient embryos. Our results reveal a critical role for Acsl4a in modulating Bmp-Smad activity and provide a potential avenue for LC-PUFAs to influence a variety of developmental processes.

Authors
Rosa Linda Miyares, Cornelia Stein, Björn Renisch, Jennifer Lynn Anderson, Matthias Hammerschmidtsend email, Steven Arthur Farbersend emailSee Affiliations

This work was supported by the NIH, the Carnegie Institution for Science, the G. Harold and Leila Y. Mathers Charitable Foundation, the German Research Foundation, and the European Union 7th Framework Program Integrated Project.

The Carnegie Institution for Science is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.