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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 Sept 17, 2014

There are two classes of dyneins, one - cytoplasmic dynein,- participates in vesicle movement
and organelle placement. The other - ciliary dynein - is very important to the function of cilia.
Loss-of-function mutations in ciliary dynein leads to Kartagener’Syndrome.
This condition typically involves severe lung disease and sterility in males.
Image credit: University of Kansas Medical Center

 






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A molecular motor for human development

Addressing another mystery of the human body, scientists have identified how a molecular motor essential for human development works. They have also found how gene mutations linked to this motor can lead to a range of human diseases.

Research from the University of Bristol now defines the composition of the human molecular motor —'cytoplasmic dynein-2' — finding it is essential to normal development. Dynein 2 directs molecules into cilia and controls those molecules movement along the cilia.


Cilia are slender protrusions that act as antennae on nearly all human cells. They are important in sensing signals that direct cell function.


Dysfunctional cilia are known to underlie a number of chronically disabling and sometimes life-threatening genetic conditions. Cilia problems affect multiple systems, causing blindness, deafness, chronic respiratory infections, kidney disease, heart disease, infertility, obesity and diabetes — causing conditions collectively known as ciliopathies. Many of these conditions are linked to childhood development. In the UK, one in every 100,000 babies is born with Jeune Syndrome — a rare genetic disorder affecting the way a child's cartilage and bones develop.

The new research, funded by the Medical Research Council and published in the Journal of Cell Science, has explained for the first time exactly how the human cytoplasmic dynein-2 motor works.


This new information could help with diagnosis, and scientists hope in the long-term to be able to alter the function of the defective motor for therapeutic benefit.


Professor David Stephens from the School of Biochemistry at the University of Bristol led the research. He points out: "The discovery of new components in the motor gives us a great opportunity towards understanding how defects in dynein-2 lead to disease."

Building upon work done in simple model organisms — such as green algae — researchers also proved that two genes associated with Jeune Syndrome (WDR34 and WDR60) are essential parts of the human version of this motor. Both genes encode proteins that are required to form the dynein-2 motor, which explains why a mutation in either gene leads to a ciliopathy. The research also identified a new component in dynein-2 (TCTEX1D2) — another candidate gene that if mutated could lead to Jeune Syndrome.

Abstract
Cytoplasmic dynein-2 is the motor for retrograde intraflagellar transport and mutations in dynein-2 are known to cause skeletal ciliopathies. Here we define for the first time the composition of the human cytoplasmic dynein-2 complex. We show that the ciliopathy genes WDR34 and WDR60 are bona fide dynein-2 intermediate chains and are both required for dynein-2 function. In addition, we identify TCTEX1D2 as a unique dynein-2 light chain that is itself required for cilia function. We define several subunits common to both dynein-1 and dynein-2 including TCTEX-1 and -3, Roadblock-1 and -3, and LC8-1 and -2 light chains. We also find that NudCD3 associates with dynein-2 as it does with dynein-1. In contrast, the common dynein-1 regulators dynactin, LIS1, or BICD2 are not found in association with dynein-2. These data explain why mutations in either WDR34 or WDR60 cause disease as well as identifying TCTEX1D2 as a candidate ciliopathy gene.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.

Paper
'Subunit composition of the human cytoplasmic dynein-2 complex' by David Asante, Nicola L. Stevenson and David J. Stephens in the Journal of Cell Science.

More information on ciliopathies can be found on the Ciliopathy Alliance website.

About the Medical Research Council (MRC)
The Medical Research Council has been at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers' money in some of the best medical research in the world across every area of health. Twenty-nine MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed. Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. http://www.mrc.ac.uk



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