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!




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 April 21, 2014


For the first time researchers have used infant hair to examine the uterine hormonal
environment. Hair closest to the scalp reveals the most recent information but moving
down the shaft effectively transits across an individual's hormonal timeline.

WHO Child Growth Charts




Newborn hair gives clues about life in the womb

A team of researchers have found that infant hair contains a history of the rich hormonal environment in which the fetus was growing. A potential diagnostic tool for that child's future.

Like rings of a tree, hair can reveal a lot of information. It can tell if an athlete was doping - or provide information about hormones and environmental toxins affecting a person. A team of University of Wisconsin-Madison researchers show in a study of rhesus monkeys, published in the journal Pediatric Research, hair can also reveal the uterine environment in which an infant formed.

This is the first time researchers have used infant hair to examine the  uterine hormonal environment and promises to yield a wealth of new information significant to many fields, from neonatology to psychology, social science to neurology. Hair closest to the scalp reveals the most recent information but moving down the shaft effectively transits across an individual's hormonal timeline.

"We had this 'Aha!' realization that we could use hair in newborns, because it starts growing one to two months before birth. It provides a glimpse of the prenatal hormone environment."

Christopher Coe, PhD, professor of psychology, director of Harlow Center for Biological Psychology at the University of Wisconsin Madison

For the noninvasive study, researchers took small samples of hair from mother rhesus monkeys and their infants using common hair clippers. The hair was cleaned and pulverized into a fine powder using a high-speed grinder. Then each sample was passed through a mass spectrometry machine to reveal that individual's hormonal signature.

Researchers were interested in what differences there were in the hormones of infants born to first-time mothers versus mothers with several births. They compared monkey mothers equivalent in age to 15-year-old humans and those monkeys similar in age to pregnant young adult humans.

"The research provided a model of teenage pregnancy. As a 15 year old who is pregnant, you are still growing yourself and in competition with your developing baby for your body's nutrition."

Christopher Coe, PhD

It's well known that maternal age plays a role in pregnancy and delivery outcomes. A growing body of evidence shows that levels of some hormones – the stress hormone cortisol and female-typical hormones like estrogen – are higher in young women pregnant for the first time.

Prior studies have also shown high levels of cortisol, and drugs similar to it, can have a lasting impact on the developing brain. This includes impairment to reflexes, attention span, and an increased incidence of emotional and learning problems. Hair is non-toxic and stable at room temperature, it's easy to store and transport, so it makes an almost ideal resource. Except that human infants have a lot less than rhesus monkeys.

In the monkey study, researchers found that cortisone, an inactive form of cortisol, was higher in young mothers and in their babies than in the hair of older mothers and their babies.

Babies born to young mothers also had higher levels of estrone (a form of estrogen) and testosterone in their hair than did babies born to older mothers. Levels of both these hormones were surprisingly similar between male and female infants.

Both Coe and Amita Kapoor, first author of the study and former postdoctoral researcher in Coe's lab, are particularly interested in whether these differences impact "maleness and femaleness" of the babies: Does higher exposure to these steroid hormones during fetal development lead to more pronounced gender differences in behavior later in life.

Their findings address questions about everything from the significance of birth order to stereotypical "boy" and "girl" behaviors in children. Additionally, what happens to a developing fetus while in the womb may impact its risk for chronic disease later in life, says Kapoor.

"Type 2 diabetes, metabolic disease, coronary artery disease, psychiatric disorders – there [may be] a whole host of long-term repercussions of stress to the fetus in utero."

Amita Kapoor, assistant researcher, Wisconsin National Primate Research Center's Assay Services.

Kapoor's comments refer to a theory proposed by the epidemiologist David Barker suggesting the sexual orientation of a developing fetus may be "programmed" in response to the womb environment.

For this rhesus study, Kapoor, along with colleague Curtis Hedman of the Wisconsin State Laboratory of Hygiene, was able to refine a new method for looking at multiple hormones at a time. She was able to analyze eight hormones simultaneously and is now working to increase that number.

For Christopher Coe, this "proof-of-concept" study provides a new world of opportunity for answering questions. Such as: "How does the prenatal environment set the stage for risk or resilience to disease?"

Growth trajectories established early in life have proven to be important determinants of metabolism, health in adulthood, and ultimate mortality. The age of sexual maturation may also be set early in development, perhaps etched in utero. The following study used growth curve modeling to investigate the degree to which birth weight and weight gain before sexual maturation constrained the timing of reproduction in 147 female rhesus monkeys living under standardized social and nutritional conditions. Although size at birth by itself did not determine age of reproductive maturation, it was strongly associated with the subsequent developmental growth trajectory, which in turn predicted age at first offspring. In contrast to human studies indicating that small birth size is followed by a postnatal “catch-up” growth phase that accelerates menarche, growth trajectories remained distinctive in small and large infant monkeys. Thus, it was the sustained and stable disparity in size already evident at birth and amplified through development that accounted for variation in the age of adult sexual maturity.

Return to top of page