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 in 1993 as a first generation internet teaching tool consolidating human embryology teaching for first year medical students.

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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Hunger-spikes and autoimmune diseases

Neurons that control hunger in the central nervous system also regulate immune cells, implicating eating behavior as a defense against infections and autoimmune disease. Autoimmune diseases are on a steady rise in the United States. These illnesses develop when the body's immune system turns on itself. Interactions between different T cells are at the heart of fighting infections, but have also been linked to autoimmune disorders.

Yale School of Medicine researchers have published the new work in the Proceedings of the National Academy of Sciences (PNAS).

"We've found that if appetite-promoting AgRP neurons are chronically suppressed, leading to decreased appetite and a leaner body weight, T cells are more likely to promote inflammation-like processes enabling autoimmune responses that could lead to diseases like multiple sclerosis," said lead author Tamas Horvath, the Jean and David W. Wallace Professor of Biomedical Research and chair of comparative medicine at Yale School of Medicine.

"If we can control this mechanism by adjusting eating behavior and the kinds of food consumed, it could lead to new avenues for treating autoimmune diseases," he added.

Horvath and his research team conducted their study
in two sets of transgenic mice. In one set, they knocked
out Sirt1, a signaling molecule that controls the hunger-
promoting neuron AgRP in the hypothalamus.

These Sirt1-deficient mice had decreased regulatory
T cell function and enhanced effector T cell activity,
leading to their increased vulnerability in an
animal model of multiple sclerosis.

"This study highlights the important regulatory role of the neurons that control appetite in peripheral immune functions," said Horvath. "AgRP neurons represent an important site of action for the body's immune responses."

The team's data support the idea that achieving weight loss
through the use of drugs that promote a feeling of fullness
"could have unwanted effects on the spread
of autoimmune disorders,"
Tamas Horvath, Yale School of Medicine.

Other authors on the study include Giuseppe Matarese, Claudio Procaccini, Ciro Menale, Jae Geun Kim, Jung Dae Kim, Sabrina Diano, Nadia Diano, Veronica De Rosa, and Marcelo O. Dietrich.

The study was funded by grants from the NIH Director's Pioneer Award.

Citation: PNAS doi: 10.1073/pnas.1216044110 http://www.pnas.org/content/early/recent.

Original article: http://news.yale.edu/2013/03/25/hunger-spiking-neurons-could-help-control-autoimmune-diseases