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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Progesterone May Make Pregnacies More Vulnerable to Infections

New research shows that the progesterone receptor regulates helper T cells required for developing antibodies protecting us against disease

Women who are pregnant or using synthetic progesterone birth control injections have a conspicuous vulnerability to certain infections including malaria, Listeria, HIV, and herpes simplex virus.

A new research report appearing in the March 2013 issue of the Journal of Leukocyte Biology offers strong evidence for a possible explanation.

The progesterone receptor, a pregnancy hormone sensor,
targets a part of the immune system responsible for
protection against infections including malaria, Listeria,
HIV, herpes simplex virus and other invaders.

In addition to helping explain why some women are more
vulnerable to certain infections, it also sheds light on why
some autoimmune diseases, notably rheumatoid arthritis
and multiple sclerosis, often go into remission
during pregnancy.

"We hope that continued work in this area will ultimately yield better approaches to the prevention of immunological complications of pregnancy, safer and more effective forms of hormonal birth control and novel biological targets for the treatment of autoimmune diseases," said Grant C. Hughes, M.D., a researcher involved in the work from the Division of Rheumatology and Department of Immunology at the University of Washington in Seattle, WA.

To make their discovery, scientists used two groups of mice.

The first group had a mutated progesterone receptor, or PR gene, which rendered the mice's bodies incapable of sensing progesterone through PR (PR knockout mice). The second group was comprised of normal mice. After various forms of immunization, antibody responses were tracked.

When compared to normal mice, PR knockout mice produced much higher antibody levels, but only in response to forms of immunization requiring T cells, a cell type that normally boosts antibody production by B cells.

This prompted a closer look at B and T cells from the PR knockout mice. The researchers saw that when stimulated in the test tube, knockout B cells showed normal, if not slightly less, antibody production compared to controls.

On the other hand, knockout T cells stimulated in the test tube showed a conspicuous over-production of interferon-gamma, an inflammatory molecule involved in fighting off pregnancy-associated pathogens and in shaping protective antibody responses.

"Pregnancy and hormones have long been known to influence immune responses, but these processes have been poorly understood," said John Wherry, Ph.D., Deputy Editor of the Journal of Leukocyte Biology. "This new work is significant for two reasons. First, the identification of progesterone receptors as a mechanism of immune modulation during pregnancy sheds light on the pregnancy-immune phenomenon, and second, these studies define a potentially new target to modulate autoimmunity and immune-mediated problems during pregnancy."

The Journal of Leukocyte Biology publishes peer-reviewed manuscripts on original investigations focusing on the cellular and molecular biology of leukocytes and on the origins, the developmental biology, biochemistry and functions of granulocytes, lymphocytes, mononuclear phagocytes and other cells involved in host defense and inflammation. The Journal of Leukocyte Biology is published by the Society for Leukocyte Biology.

Details: Grant C. Hughes, Edward A. Clark, and Alan H. Wong. The intracellular progesterone receptor regulates CD4+ T cells and T cell-dependent antibody responses. J Leukoc Biol March 2013 93:369-375, doi:10.1189/jlb.1012491 ; http://www.jleukbio.org/content/93/3/369.abstract

Original article: http://www.eurekalert.org/pub_releases/2013-02/foas-pmb022813.php