Welcome to The Visible Embryo



Home-- -History-- -Bibliography- -Pregnancy Timeline- --Prescription Drugs in Pregnancy- -- Pregnancy Calculator- --Female Reproductive System- -Contact

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!




Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

Contact The Visible Embryo

News Alerts Archive

Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.
Content protected under a Creative Commons License.

No dirivative works may be made or used for commercial purposes.


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 April 17, 2014


Specially-designed motor neurons created from stem cells, were injected into injured
nerve motor neurons. The new motor neurons are designed to react to pulses of blue light —
allowing scientists to fine-tune muscle control by adjusting light intensity,
duration and frequency of impulse.

WHO Child Growth Charts




Stem cell light-activated neurons restore muscle function

The potential to restore function to muscles paralysed by conditions such as motor neuron disease and spinal cord injury, is being developed by scientists at University College London and King’s College London. Additionally, the scientists can artificially control these new muscles with light.

Muscles are normally controlled by motor neurons, specialized nerve cells within the brain and spinal cord. These neurons relay signals from the brain to muscles to bring about motor functions such as walking, standing and even breathing. However, motor neurons can become damaged by motor neuron disease or following spinal cord injuries, causing permanent loss of muscle function that results in paralysis.

A new technique combines the making of specially-designed motor neurons derived from stem cells, then transplanting these new motor neuron cells into injured nerves. The technique may lead not only to a future for muscle injury rehabilitation, but one that uses light to adjust motor neural control. As these motor neurons are also designed to react to pulses of blue light, scientists can fine-tune muscle control by adjusting the intensity, duration and frequency of light pulses to the motor neurons.

The light-responsive motor neurons that made the technique possible were created from stem cells by Dr. Ivo Lieberam of the MRC Centre for Developmental Neurobiology at King’s College London (KCL).

In the resulting study, published in Science, the team demonstrated their method using mice whose hind leg nerve muscles had been injured. The transplanted stem cell-derived motor neurons grew along the injured nerves to successfully connect to the paralyzed muscles, which then became responsive to pulses of blue light controlled by the scientists.

“Following the new procedure, we saw previously paralysed leg muscles start to function. This strategy has significant advantages over existing techniques that use electricity to stimulate nerves — as electrical stimulation can be painful, and often results in rapid muscle fatigue."

Professor Linda Greensmith of the MRC Centre for Neuromuscular Diseases at UCL’s Institute of Neurology,study co-leader.

Professor Greensmith explains further: “This new technique represents a means to restore the function of specific muscles following paralysing neurological injuries or disease.

“Within the next five years or so, we hope to undertake steps necessary to take this ground-breaking approach into human trials. Potentially, we hope to develop treatments for patients with motor neuron disease, many of whom eventually lose the ability to breathe, as their diaphragm muscles also gradually become paralysed.

"We eventually hope to use our method to create a sort of optical pacemaker for the diaphragm to keep these patients breathing.”

“We custom-tailored embryonic stem cells so that motor neurons derived from them can function as part of the muscle pacemaker device. First, we equipped the cells with a molecular light sensor. This enables us to control motor neurons with blue light flashes.

"We then built a survival gene into them, which helps the stem-cell motor neurons stay alive when they are transplanted inside an injured nerve - and allows them to grow connections into muscle.”

Dr Lieberam, co-leader of the study

Damage to the central nervous system caused by traumatic injury or neurological disorders can lead to permanent loss of voluntary motor function and muscle paralysis. Here, we describe an approach that circumvents central motor circuit pathology to restore specific skeletal muscle function. We generated murine embryonic stem cell–derived motor neurons that express the light-sensitive ion channel channelrhodopsin-2, which we then engrafted into partially denervated branches of the sciatic nerve of adult mice. These engrafted motor neurons not only reinnervated lower hind-limb muscles but also enabled their function to be restored in a controllable manner using optogenetic stimulation. This synthesis of regenerative medicine and optogenetics may be a successful strategy to restore muscle function after traumatic injury or disease.

Return to top of page