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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 6, 2014

 

De conceptu et generatione hominis 1554






WHO Child Growth Charts

 

 

 

Why girl babies win in the battle for survival

Sexual inequality between boys and girls starts as early as the womb – but how and why this occurs could be a key to preventing higher rates of preterm birth, stillbirth and neonatal death among boys.

A team from the University of Adelaide's Robinson Research Institute has been studying the underlying genetic and developmental reasons why male babies generally have worse outcomes than females, with significantly increased rates of pregnancy complications and poor health outcomes for males.


The results - published in the journal Molecular Human Reproduction - show that male and female babies develop in very different ways, and the placenta plays a key role in these gender differences.


"Our research has found that there are undeniable genetic and physiologic differences between boys and girls that extend beyond just the development of their sexual characteristics," says senior author of the paper Professor Claire Roberts, leader of the fetal growth research priority for the Robinson Research Institute.

"We've known for some time that girls are clearly winning in the battle for survival, with markedly better outcomes for female babies for preterm birth, stillbirth, neonatal death, and other complications after birth, such as macrosomia (a baby that weighs more than 4-4.5kg or 8 pounds 13 ounces at birth). Male babies generally grow faster and bigger than females. This occurs in both the animal and human worlds, but until now we haven't really understood how or why," Professor Roberts says.


The researchers investigated whether the type and pattern of genes being expressed by the placenta is different for boys and girls.

They compared the genes expressed in 300 placenta samples and found that more than 140 genes were expressed differently across male and female samples.


According to lead author and University of Adelaide PhD student Sam Buckberry:

"Our results suggest that there is a distinct sex bias in the regulation of genes in the human placenta. We found that with female babies, there is much higher expression of genes involved in placental development, the maintenance of pregnancy and maternal immune tolerance.

"This suggests that girls are more likely to adopt a risk-averse strategy towards development and survival, and it goes some way to explaining the differences in male and female development in the womb," he says.

Professor Roberts adds: "These findings may be important to help guide future sex-specific therapeutics for pregnant women and for babies in the neonatal nursery."

Abstract
As males and females share highly similar genomes, the regulation of many sexually dimorphic traits is constrained to occur through sex-biased gene regulation. There is strong evidence that human males and females differ in terms of growth and development in utero and that these divergent growth strategies appear to place males at increased risk when in sub-optimal conditions. Since the placenta is the interface of maternal–fetal exchange throughout pregnancy, these developmental differences are most likely orchestrated by differential placental function. To date, progress in this field has been hampered by a lack of genome-wide information on sex differences in placental gene expression. Therefore, our motivation in this study was to characterize sex-biased gene expression in the human placenta. We obtained gene expression data for >300 non-pathological placenta samples from 11 microarray datasets and applied mapping-based array probe re-annotation and inverse-variance meta-analysis methods which showed that >140 genes (false discovery rate (FDR) <0.05) are differentially expressed between male and female placentae. A majority of these genes (>60%) are autosomal, many of which are involved in high-level regulatory processes such as gene transcription, cell growth and proliferation and hormonal function. Of particular interest, we detected higher female expression from all seven genes in the LHB-CGB cluster, which includes genes involved in placental development, the maintenance of pregnancy and maternal immune tolerance of the conceptus. These results demonstrate that sex-biased gene expression in the normal human placenta occurs across the genome and includes genes that are central to growth, development and the maintenance of pregnancy.


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