Welcome to The Visible Embryo

Home-- -History-- -Bibliography- -Pregnancy Timeline- --Prescription Drugs in Pregnancy- -- Pregnancy Calculator- --Female Reproductive System- -Contact
 

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!



Home

History

Bibliography

Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

Contact The Visible Embryo

News Alerts Archive

Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.
Content protected under a Creative Commons License.

No dirivative works may be made or used for commercial purposes.

Return To Top Of Page
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
Google Search artcles published since 2007
 
 

Home | Pregnancy Timeline | News Alerts | News Archive June 14, 2013

 

Sperm illustrated within fallopian tube

Researchers found that offspring from paternal stress groups displayed significantly blunted
levels of the stress hormone corticosterone—in humans, it’s cortisol—in response to stress






WHO Child Growth Charts

 

 

 

Dad's Life Stress Can Affect Offspring Brain Development

Male and female offspring of stressed male mice show reduced stress response, an underlying feature of several mental disorders.

Sperm doesn’t appear to forget anything. Stress felt by dad—whether as a preadolescent or adult—leaves a lasting impression on his sperm that gives sons and daughters a blunted reaction to stress, a response linked to several mental disorders. The findings, published in a new preclinical study in the Journal of Neuroscience by researchers at the University of Pennsylvania, point to a never-before-seen epigenetic link to stress-related diseases such as anxiety and depression passed from father to child.

While environmental challenges, like diet, drug abuse, and chronic stress, felt by mothers during pregnancy have been shown to affect offspring neurodevelopment and increase the risk for certain diseases, dad’s influence on his children are less well understood. The effects of lifelong exposures to dad on children are even more out of reach.


Now, a team of researchers led by Tracy L. Bale, PhD, associate professor of neuroscience in the Perelman School of Medicine Department of Psychiatry and the School of Veterinary Medicine Department of Animal Biology have shown that stress on preadolescent and adult male mice induced an epigenetic mark in their sperm that reprogrammed their offspring’s hypothalamic-pituitary-adrenal (HPA) axis, a region of the brain that governs responses to stress.

Surprisingly, both male and female offspring had abnormally low reactivity to stress.

This stress pathway dysregulation—when reactivity is either heightened or reduced—is a sign that an organism doesn’t have the ability to respond appropriately to a changing environment. And as a result, their stress response becomes irregular, which can lead to stress-related disorders.


“It didn’t matter if dads were going through puberty or in adulthood when stressed before they mated. We’ve shown here for the first time that stress can produce long-term changes to sperm that reprogram the offspring HPA stress axis regulation,” said Bale. “These findings suggest one way in which paternal-stress exposure may be linked to such neuropsychiatric diseases.”

Past epidemiological studies suggest that germ cells—sperm and eggs—are more susceptible to reprogramming during the slow growth period of preadolescence. Therefore, in this study, in order to examine the effects of paternal stress, male mice were exposed to six weeks of chronic stress, before breeding, either throughout puberty or only in adulthood. Examples of stress include sudden move to another cage, predator oder (fox urine, for example), noise, or a foreign object in the cage.

Male mice are ideal for such an experiment because they do not participate in offspring rearing, meaning any external factors outside of germ-cell formation are essentially eliminated.

Researchers found that offspring from paternal stress groups displayed significantly blunted levels of the stress hormone corticosterone—in humans, it’s cortisol—in response to stress.

To understand the neural circuitry in the offspring, the group also examined changes in gene expression in certain brain regions involved in stress regulation: the paraventricular nucleus (PVN) and the bed nucleus of stria terminals. They found an increased expression of glucocorticoid-responsive genes in the PVN, a change that supports a possible mechanism whereby increased negative feedback sensitivity may be explained.


The researchers also looked at a series of microRNAs (miRs) in the sperm that uniquely contribute to post-fertilization gene expression in order to examine the epigenetic mechanisms of transmission to the next generation.

In both groups of stressed dads, there was a significant increase in expression of nine miRs. These miRs may be targeting the stored maternal messenger RNAs in the egg at fertilization, so that dad’s sperm regulates some aspect of early development to inform his offspring about the environment, according to the authors.

They also point out that a reduced physiological stress response may reflect some adaptive evolutionary benefit passed on to offspring to ensure survival in what is expected to be a more stressful environment.


“Whether such diminished stress reactivity would be detrimental or beneficial to offspring likely depends on the environment into which they were born, as well as genetic background factors,” they state in the paper. However, they conclude, the finding that mild stress experience across a lifespan can change in male germ cells provides an important and novel mechanism contributing to neuropsychiatric disease risk.

“Next, we are examining the mechanism whereby these sperm miRs act at fertilization, and then we can think about using them as biomarkers in human diseases,” said Bale. “And then we can begin to predict who has been exposed to what, and to think about prevention or treatment down the road.”

Co-authors of the study include Ali B. Rodgers, Christopher P. Morgan, Stefanie L. Bronson, and Sonia Revello, also of the Department of Animal Biology, School of Veterinary Medicine at Penn.

This work was supported by NIH grants MH087597, MH091258, and MH099910.

Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $4.3 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 16 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $398 million awarded in the 2012 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania -- recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; and Pennsylvania Hospital -- the nation's first hospital, founded in 1751. Penn Medicine also includes additional patient care facilities and services throughout the Philadelphia region.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2012, Penn Medicine provided $827 million to benefit our community.

Original press release: http://www.uphs.upenn.edu/news/News_Releases/2013/06/bale/