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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.

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Pregnancy Timeline by SemestersFemale Reproductive SystemFertilizationThe Appearance of SomitesFirst TrimesterSecond TrimesterThird TrimesterFetal 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 HemispheresEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterDevelopmental Timeline
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September 13, 2012--------News Archive Return to: News Alerts


Carnegie Stage 4

5 to 6 days post ovulation, the blastocyst enters the uterus, the outer layer of
trophoblast cells secrete an enzyme to erode the epithelial lining
of the uterus and allow the blastocyst to implant.
Trophoblast cells are critical to forming the placenta.

WHO Child Growth Charts

       

Marijuana Use Implicated in Preeclampsia

New research indicates marijuana-like compounds called endocannabinoids alter genes and biological signals critical to the formation of a normal placenta during pregnancy - and may contribute to pregnancy complications like preeclampsia


The study offers evidence that abnormal signaling
of endocannabinoid lipid molecules
disrupts the movement of early embryonic cells,
in particular trophoblast cells that form the placenta.

Abnormal placental function is common in preeclampsia
– a medical condition of unknown cause
that is a danger to mother and child.


The study appears in the Sept. 14 edition of The Journal of Biological Chemistry

The research – from scientists in the Division of Reproductive Sciences at Cincinnati Children's Hospital Medical Center – analyzed mouse preimplantation embryos mutated to alter endocannabinoid signaling. They found that either silencing or enhancing endocannabinoid signaling adversely affects trophoblast stem cell migration.


"Our findings raise concerns that exposure to cannabis
products may adversely affect early embryo development
that is then perpetuated later in pregnancy,"

Sudhansu K. Dey, PhD.
principal investigator, division director.


"Also, given that endocannabinoid signaling plays a key role in the central nervous system, it would be interesting in future studies to examine whether affected cell migration-related genes in early embryos also participate in neuronal cell migration during brain development."

Along with co-first authors Huirong Xie and Xiaofei Sun, Dey and other members of the research team studied mouse embryos that had not yet implanted inside the uterus of the mother. Previous research by Dey's laboratory has shown the timing of critical events in early pregnancy, including when and how well an embryo implants in the uterus, is vital to a healthy pregnancy and birth.

In the current study, researchers conducted DNA microarray analyses to determine how the expression levels of genes important to healthy embryo development were affected in embryos with abnormal endocannabinoid signaling.

In one group of embryos endocannabinoid signaling was silenced by deleting the gene Cnr1, which activates endocannabinoid signaling processes. A second group of mice was mutated to produce elevated endocannabinoid levels similar to that observed in wild type mice treated with tetrahydrocannabinol (THC), the active psychotropic agent in cannabis. This was done by deleting the gene Faah, which breaks down molecules that activate endocannabinoid signaling.


In both groups, the expression of numerous genes
known to be important to cell movement and
embryo development was lower than in normal
(wild type) mice. This included the development
and migration of trophoblast stem cells.

Trophoblast cells help anchor the conceptus
with the uterus and also form much of the placenta,
critical to establishment of maternal-fetal circulation
and exchange of nutrients.


Researchers said mouse models developed for the current study (with silenced and elevated endocannabinoid signaling) may help advance more extensive studies on the causes of preeclampsia.

Funding for the research was supported by grants from National Institute on Drug Abuse/National Institutes of Health (DA006668), the March of Dimes and a postdoctoral fellowship from the Lalor Foundation.

Original article: http://www.eurekalert.org/pub_releases/2012-09/cchm-sim091212.php