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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 Nov 18, 2013

 

Image of non-diabetic healthy human islet cells that reside in pancreas. Insulin-producing beta cells are stained green.

Image Credit: Gökhan S. Hotamisligil lab/Harvard University.







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New approach to prevent type 1 diabetes

Experimental findings could lead to new, inexpensive therapy using a naturally occurring bile acid.

New research led by Harvard School of Public Health (HSPH) demonstrates a disease mechanism in type 1 diabetes (T1D) that can be targeted using simple, naturally occurring molecules to help prevent the disease.

The work highlights a previously unrecognized molecular pathway that contributes to the malfunction of insulin-producing pancreatic beta cells in T1D in human patients and in mice, and shows that a chemical intervention can help beta cells function properly and survive. Currently, there is no preventive regimen or cure for T1D, and the only treatment is insulin therapy by injection or pump.

The study appears online November 13, 2013 in Science Translational Medicine.

In T1D, beta cells are mistakenly attacked by the body's own immune system, and much prior research has focused on ways to prevent this autoimmune response.


"This study breaks new ground because it focuses on boosting beta cell performance and shows that beta cell preservation is possible even in the face of such immune attack,"

Gökhan S. Hotamisligil, senior author, chair of the Department of Genetics and Complex Diseases and J.S. Simmons Professor of Genetics and Metabolism at HSPH.


It's estimated that as many as three million Americans have T1D. According to the National Institute of Diabetes and Digestive and Kidney Diseases, each year more than 15,000 children and 15,000 adults—roughly 80 people per day—are diagnosed with the disease in the U.S. And the numbers are on the rise: according to the U.S. Centers for Disease Control and Prevention, the disease's prevalence in Americans under age 20 rose by 23% between 2001 and 2009.

Using human pancreatic samples and mouse models, the HSPH researchers—with colleagues from Harvard Medical School, the Broad Institute of Harvard and MIT, and the Université Libre de Bruxelles—sought to tease apart the mechanisms of beta cell failure in T1D. They honed in on the function of the endoplasmic reticulum (ER)—a "mini-organ" inside cells where proteins and lipids are processed and packaged and undergo quality control before they reach their destinations in the body. The ER is known to play a critical role in supporting the work of beta cells.

The researchers found that, in animal models and in humans with T1D, ER function is compromised by the immune attack. This reduced ER function results in ER stress and contributes to the death of beta cells and the insulin insufficiency that is characteristic of T1D.


In earlier studies, researchers in the Hotamisligil lab showed that ER stress in other tissues plays a key role in obesity and type 2 diabetes, and can be corrected with so-called "chemical chaperones" such as tauroursodeoxycholic acid (TUDCA), a bile acid.


Based on that previous research, the scientists applied TUDCA to mouse models of T1D and found that ER function improved—both in mice with diabetes and those with pre-diabetes. Beta cells functioned better and were less likely to die, and, to the researchers' surprise, the treated mice had a dramatically reduced incidence of T1D. Researchers also identified the specific molecular pathway through which TUDCA influences ER function.

"The study is exciting because it suggests that improving ER function before the onset of disease could reduce T1D incidence," said lead author Feyza Engin, research associate in the HSPH Department of Genetics and Complex Diseases.

Advances in medicine now allow physicians to identify, with great accuracy, those with very high risk for developing T1D. "There is really a need for some safe and mild interventions that can prevent emergence of type 1 diabetes in these populations," said Hotamisligil.


"TUDCA is safe and inexpensive. It's possible that TUDCA or another molecule that acts via the described mechanisms could be used as a novel therapeutic approach to keep those at risk for type 1 diabetes disease-free for long periods of time, or could even prevent the disease all together."

Gökhan S. Hotamisligil, senior author


Abstract
Perturbations in endoplasmic reticulum (ER) homeostasis can evoke stress responses leading to aberrant glucose and lipid metabolism. ER dysfunction is linked to inflammatory disorders, but its role in the pathogenesis of autoimmune type 1 diabetes (T1D) remains unknown. We identified defects in the expression of unfolded protein response (UPR) mediators ATF6 (activating transcription factor 6) and XBP1 (X-box binding protein 1) in β cells from two different T1D mouse models and then demonstrated similar defects in pancreatic β cells from T1D patients. Administration of a chemical ER stress mitigator, tauroursodeoxycholic acid (TUDCA), at the prediabetic stage resulted in a marked reduction of diabetes incidence in the T1D mouse models. This reduction was accompanied by (i) a significant decrease in aggressive lymphocytic infiltration in the pancreas, (ii) improved survival and morphology of β cells, (iii) reduced β cell apoptosis, (iv) preserved insulin secretion, and (v) restored expression of UPR mediators. TUDCA’s actions were dependent on ATF6 and were lost in mice with β cell–specific deletion of ATF6. These data indicate that proper maintenance of the UPR is essential for the preservation of β cells and that defects in this process can be chemically restored for preventive or therapeutic interventions in T1D.

Copyright © 2013, American Association for the Advancement of Science
Citation: F. Engin, A. Yermalovich, T. Nguyen, S. Hummasti, W. Fu, D. L. Eizirik, D. Mathis, G. S. Hotamisligil, Restoration of the Unfolded Protein Response in Pancreatic β Cells Protects Mice Against Type 1 Diabetes. Sci. Transl. Med. 5, 211ra156 (2013).

Other HSPH authors included Alena Yermalovich, Truc Nguyen, and Sarah Hummasti, all members of the Hotamisligil lab.

Funding for this project was provided by JDRF (17-2008-901); National Institutes of Health PO1 (A1054904); the European Union; the Fonds National de la Recherche Scientifique; and Schuylar funds.

"Restoration of the Unfolded Protein Response in Pancreatic β Cells Protects Mice Against Type 1 Diabetes," Feyza Engin, Alena Yermalovich, Truc Nguyen, Sarah Hummasti, Wenxian Fu, Decio L. Eizirik, Diane Mathis, and Gökhan S. Hotamisligil, Science Translational Medicine, Vol. 5, Issue 211, online November 13, 2013

Visit the HSPH website for the latest news, press releases and multimedia offerings.

Harvard School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory and the classroom to people's lives—not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at HSPH teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as the oldest professional training program in public health.