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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.

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!




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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
Google Search artcles published since 2007

Home | Pregnancy Timeline | News Alerts |News Archive Oct 8, 2014

(BLUE) Dissection of the larval zebrafish skeleton shows facial cartilage
and bone (RED)  Zebrafish Image courtesy of the Crump Lab.
Inset image: Carnegie Stage 12 in Human Development - The Visible Embryo


WHO Child Growth Charts




One gene error affects immunity/face development

How a face forms — or misforms — during early development is still being discovered. Recent research has begun to unwind some of the mystery of how cells migrate into position to become major facial structures AND part of our immune system.

In the journal Development, a project  explains how a mutation in the gene TBX1 causes facial deformities as well as immune system errors to the Thymus gland, all problems found in DiGeorge syndrome.

DiGeorge Syndrome is an immunodeficiency disease caused by abnormal migration of cells and subsequent abnormal development during fetal development.

One of the defects appears in the thymus gland ending in low T-lymphocytes and causing frequent infections.

During prenatal development, a series of structures are being organized into features of the face. These structures, or “pouches,” are made from epithelial tissue which also forms into our skin, glands and linings of organs like the lungs, heart and intestines.

In mice and zebrafish with TBX1 gene mutation, facial pouches improperly develop and the face is deformed.

In humans, deformities can include an underdeveloped chin, eyes with heavy eyelids, ears that are rotated back and small upper portions to the ear. But facial characteristics vary greatly from person to person. Many patients do not even have prominent deformities.

Chong Pyo Choe, postdoctoral fellow under J. Gage Crump, principal investigator for the project, used sophisticated time-lapse imaging to observe how TBX1 influences other genes. One gene affected, called Fgf8a, attracts pouch-forming cells into correct alignment to grow into specific facial features. Errors in TBX1creates errors in Fgf8a and thus in the allignment of cells in the face.

“It had previously been recognized that mutations in TBX1 underlie DiGeorge syndrome in patients, but our study reveals that this master control gene organizes complex cell arrangements to build the face as well.”

Gage Crump PhD, associate professor, principal investigator, the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California.

The pharyngeal pouches are a segmental series of epithelial structures that organize the embryonic vertebrate face. In mice and zebrafish that carry mutations in homologs of the DiGeorge syndrome gene TBX1, a lack of pouches correlates with severe craniofacial defects, yet how Tbx1 controls pouch development remains unclear. Using mutant and transgenic rescue experiments in zebrafish, we show that Tbx1 functions in the mesoderm to promote the morphogenesis of pouch-forming endoderm through wnt11r and fgf8a expression. Consistently, compound losses of wnt11r and fgf8a phenocopy tbx1 mutant pouch defects, and mesoderm-specific restoration of Wnt11r and Fgf8a rescues tbx1 mutant pouches. Time-lapse imaging further reveals that Fgf8a acts as a Wnt11r-dependent guidance cue for migrating pouch cells. We therefore propose a two-step model in which Tbx1 coordinates the Wnt-dependent epithelial destabilization of pouch-forming cells with their collective migration towards Fgf8a-expressing mesodermal guideposts.

All work reported on in this article was conducted at the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at the University of Southern California.

Funding for this study came from a National Institute of Dental and Craniofacial Research (NIDCR) grant (R01DE022572) and a California Institute for Regenerative Medicine (CIRM) training fellowship.

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