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.

 

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 Nov 11, 2013

 

Infants' immune systems are suppressed while microbes colonize their bodies.







WHO Child Growth Charts

 

 

 

New explanation for infection susceptibility in newborns

Cells that allow helpful bacteria to safely colonize the intestines of newborn infants also suppress their immune systems to make them more vulnerable to infections.

The study, which appears online Nov. 6, in Nature, could prompt a major shift in how medicine views the threat of neonatal infections – and how researchers go about looking for new strategies to stop infection, say scientists at Cincinnati Children's Hospital Medical Center.

Until now, the prevailing view has been that newborn infants are susceptible to infection because their immune system cells are immature or underdeveloped.


"The first few days after birth represent a critical developmental period when a baby's immune system must adapt to many new stimulants. This includes environmental microbes that are not present in the womb, but immediately colonize tissues such as the intestine and skin.

"Our findings fundamentally change how we look at neonatal susceptibility to infection by suggesting it is caused by active immune suppression during this developmental period, as opposed to the immaturity of immune cells."

Sing Sing Way, MD, senior investigator, physician, Division of Infectious Diseases, Cincinnati Children's Hospital


CD71+ are immune suppressive cells which are precursors to mature red blood cells — found  in newborn mice and human umbilical cord blood. CD71+ cells prevent an over reactive immune response in infants as they adapt to their new microbe-filled world. tThey do this through expression of an enzyme called arginase-2 — essential to suppress immune cells. This process is vital to developing infants' intestines as it prevents the onslaught of inflammation response to colonizing bacteria which help digestion.

Researchers used a series of laboratory tests in human blood cells and mouse models to show how immune suppression in newborns extends beyond the intestines to affect other parts of the body. Although newborn vulnerability to infection is well known, Way began his study because earlier research had shown that compromised immunity in infant mice varies significantly on specific experimental conditions. This led the authors to hypothesize that there must be a better explanation for compromised immunity in neonates besides pointing to immature immune cells.

The scientists transferred adult immune system cells in bulk from adult mice into newborn mice to see if this would boost neonatal immunity during exposure to infection. Instead of enhancing immunity, researchers said the production of protective immune system cytokines in the adult cells remained blunted in the newborn mice. Similar results were observed when adult immune cells were mixed with neonatal cells in laboratory cultures.

In a complementary experiment, researchers transferred newborn immune system cells into adult mice exposed to infection. In the adult mice, the neonatal immune cells produced the protective cytokine TNF-alpha, which helps ramp up the immune system's protective response against infection.

Way and his colleagues said the benefits of CD71+ immune suppression to allow healthy bacterial colonization of intestines are essential, and this outweighs the threat of systemic infant infections. But the researchers stressed the importance of follow up studies to develop new strategies for protecting newborns from systemic infections. The goal would be to offer this protection while still allowing CD71+ cells to do their job in helping develop healthy intestines.

One strategy being explored by investigators in their ongoing research is possible modulation or control of immune suppression by CD71+ cells. The authors were careful to emphasize that far more follow up study is needed before direct application of their findings to human infants.

Abstract
Newborn infants are highly susceptible to infection. This defect in host defence has generally been ascribed to the immaturity of neonatal immune cells; however, the degree of hyporesponsiveness is highly variable and depends on the stimulation conditions1, 2, 3, 4, 5, 6, 7. These discordant responses illustrate the need for a more unified explanation for why immunity is compromised in neonates. Here we show that physiologically enriched CD71+ erythroid cells in neonatal mice and human cord blood have distinctive immunosuppressive properties. The production of innate immune protective cytokines by adult cells is diminished after transfer to neonatal mice or after co-culture with neonatal splenocytes. Neonatal CD71+ cells express the enzyme arginase-2, and arginase activity is essential for the immunosuppressive properties of these cells because molecular inhibition of this enzyme or supplementation with L-arginine overrides immunosuppression. In addition, the ablation of CD71+ cells in neonatal mice, or the decline in number of these cells as postnatal development progresses parallels the loss of suppression, and restored resistance to the perinatal pathogens Listeria monocytogenes and Escherichia coli8, 9. However, CD71+ cell-mediated susceptibility to infection is counterbalanced by CD71+ cell-mediated protection against aberrant immune cell activation in the intestine, where colonization with commensal microorganisms occurs swiftly after parturition10, 11. Conversely, circumventing such colonization by using antimicrobials or gnotobiotic germ-free mice overrides these protective benefits. Thus, CD71+ cells quench the excessive inflammation induced by abrupt colonization with commensal microorganisms after parturition. This finding challenges the idea that the susceptibility of neonates to infection reflects immune-cell-intrinsic defects and instead highlights processes that are developmentally more essential and inadvertently mitigate innate immune protection. We anticipate that these results will spark renewed investigation into the need for immunosuppression in neonates, as well as improved strategies for augmenting host defence in this vulnerable population.


Funding for the study came from the National Institute of Allergy and Infectious Diseases (R01AI087830, R01AI100934), the National Heart Lung and Blood Institute (R01HL103745) and the Burroughs Wellcome Fund.

About Cincinnati Children's:
Cincinnati Children's Hospital Medical Center ranks third in the nation among all Honor Roll hospitals in U.S. News and World Report's 2013 Best Children's Hospitals ranking. It is ranked #1 for cancer and in the top 10 for nine of 10 pediatric specialties. Cincinnati Children's, a non-profit organization, is one of the top three recipients of pediatric research grants from the National Institutes of Health, and a research and teaching affiliate of the University of Cincinnati College of Medicine. The medical center is internationally recognized for improving child health and transforming delivery of care through fully integrated, globally recognized research, education and innovation. Additional information can be found at http://www.cincinnatichildrens.org. Connect on the Cincinnati Children's blog, via Facebook and on Twitter.

Original press release: http://www.cincinnatichildrens.org/news/release/2013/infant-immunity-nature-11-06-2013/