Carnegie Stages - 2nd Trimester Pregnancy3rd Trimester Pregnancy3rd Trimester PregnancyCarnegie Stage 1 - Fertilization Carnegie Stage 2 - CleavageCarnegie Stage 3 - Early BlastocystCarnegie Stage 4 - ImplantationCarnegie Stage 5 - Implantation CompletedCarnegie Stage 6 - GastrulationCarnegie Stage 7 - NeurulationCarnegie Stage 8 - Primitive PitCarnegie Stage 9 - First SomitesCarnegie Stage 10 - Neural Folds, Heart TubeCarnegie Stage 11 - Optic VesicleCarnegie Stage 12 - Upper Limb BudsCarnegie Stage 13 - First Layer Skin Carnegie Stage 14 - Esophagus FormingCarnegie Stage 15 - Cerebral Hemispheres FormingCarnegie Stage 16 - Hindbrain DevelopingCarnegie Stage 17 - Primitive germ cellsCarnegie Stage 19 - Semicircular Canals Forming in Inner EarCarnegie Stage 20 - Spontaneous MovementCarnegie Stage 21 - Intestines MigrateCarnegie Stage 22 - Brain can move musclesCarnegie Stage 23 - End of embryonic developmentWeeks 10 to 11 - Basic Brain Structure CompleteWeeks 12 to 13 - Fetus begins to move aroundWeeks 14 to 15 - Sexual organs now clearly visibleWeeks 16 to 17 - Fingerprints and toe prints beginWeeks 18 to 19 - Brown fat surrounds the lymphatic system.Weeks 20 to 21 - Bone marrow starts making blood cellsWeeks 22 to 23 - Inner ear bones harden, hearing possibleWeeks 24 to 25 - Sensory brain waves begin to activateWeeks 26 to 27 - Lungs begin to produce sufacantWeeks 28 to 29 - Brain Surface Convolutions BeginWeeks 39 to 40 - Baby full termWeeks 41 - 41 Baby full termWeeks 38 to 39 - Fetal liver is producing blood cellsWeeks 36 to 37 - Body is round and plump with white fatWeeks 34 to 35 - Gastrointestinal system still very immatureWeeks 32 to 33 - Fetus begins to develop immune systemWeeks 30 to 31 - Rapid brain growth; head size increasesPregnancy - 1st TrimesterPregnancy - 1st Trimester

The Visible Embryo
is a visual guide through fetal development from fertilization through pregnancy to birth. As the most profound physiologic changes occur in the "first trimester" of pregnancy, these Carnegie stages are given prominence on the birth spiral.

The shape and location of embryonic
internal structures and how they
relate and are connected to each
other is essential to understanding
human development. Medical
professionals create a mental picture
of this process in order to determine
how well the fetus is progressing. It is
also the basis of knowing how and when
errors in development occur and if a
possibility exists for a corrective

It is equally important for expectant
parents to understand the relationship
of these internal structures and how
their infant develops through pregnancy.

Creating the images for The Visible Embryo, included capturing data from slides and three dimensional structures on fetal anatomy in The National Institutes of Health, Carnegie Collection of embryos, as well as from 3D and 4D ultra sound images.

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.



The Visible Embryo Home
Fetal Timeline-     Maternal Timeline&   mNews-       Prescription Drugs in Pregnancy -    --Pregnancy Calculator-   --  Female Reproductive System--

News Alerts    Birth Spiral  A Scientific Dating Game: RNA Matchmakers  Birth Spiral  Continued Embryonic Growth Drives Aging  Birth Spiral  How Elements in DNA Regulate Cell Type  Birth Spiral  Found: Molecule that Helps Sperm Find Egg  Birth Spiral  Moms with PCOS more likely to have child with autism  Birth Spiral  Cystic Fibrosis Babies Weigh Less At Birth  Birth Spiral  Low level of omega-3 tied to preterm births  Birth Spiral  Hidden Genetic Rules For How Life Began  Birth Spiral  Predicting How One Cell Can Become Another  Birth Spiral  Profiling Each RNA  Aug 2018   Birth Spiral  Small RNA in Sperm May Ensure Embryo Implants  Birth Spiral  How Junk DNA Switches On Genes  Birth Spiral  Reversing effects of an age-associated gene  Birth Spiral  Genes Do Not Determine Fitness  Birth Spiral  Autism risk determined by state of mom's gut  Birth Spiral  Environment Affects Father's Genes & His Kids Genes  Birth Spiral  Baby's Sex Affects Pregnancy Complications  Birth Spiral  Intestinal Tether System Pulls Cells Into Place  Birth Spiral  An Essential Mechanism Generates Healthy Muscle  Birth Spiral  Closing In On Organ Formation  Birth Spiral  New species arise from rapid mitochondrial evolution!  Birth Spiral  Mammalian life begins differently than we thought!  Birth Spiral  Cured! A genetic blood disorder stopped in utero  Birth Spiral  Mighty mitochondria flex their DNA power  Birth Spiral  Testosterone is not strictly controlled by genetics  Birth Spiral  A New way to turn skin cells into stem cells  Birth Spiral  Taking hormones affects your DNA  Birth Spiral  MTSS1 protein controls neuron branching  Birth Spiral  Placenta equalizes growth rate in embryo  Birth Spiral  Stem cell to functional heart: The Mesp1 gene  Birth Spiral  Turing patterns in biology  Birth Spiral  'Jumping genes' are critical to early embryo  Jul 2018   Birth Spiral  Brown fat flexes its muscle  Birth Spiral  Unlocking Secrets of Cell Aging  Birth Spiral  Tracking Brain Signals That Drive Language  Birth Spiral  Fetal Brain Subplate Disappears!  Birth Spiral  Our Early Development of Memory  Birth Spiral  Mom's love good for child's brain  Birth Spiral  Fetal T cells are first responders to infection in adults  Birth Spiral  3D Computer Model of Breast Duct Formation  Birth Spiral  Neurons have antennae?  Birth Spiral  How to build a brain  Birth Spiral  The 3D Nucleus  Birth Spiral  Why do we need a pair of genome?  Birth Spiral  Ancestor Genes May Trigger Breast Cancer  Birth Spiral  Some blood stem cells are better than others  Birth Spiral  Fructose doesn't affect our body like sugar does  Birth Spiral  New Insights Into Human Evolution  Birth Spiral  3 Genes, found only in humans, influence brain size  Birth Spiral  New copies of old gene began our brain expansion  Birth Spiral  Mom's stem cells may save her baby   Birth Spiral  Free treatment for children with Progeria  Birth Spiral  The surprise about cell death/apoptosis  June 2018   Birth Spiral  Closing coal, oil power plants = healthier babies  Birth Spiral  A Test to Predict Preterm Birth  Birth Spiral  Meet the Master Organizers of Human Embryo Growth  Birth Spiral  You Are What Your Mother Eats  Birth Spiral  What's changed about the nucleolus since high school ?  Birth Spiral  600 Million Year Old Molecular Principles  Birth Spiral  How to 'transfer' a memory  Birth Spiral  Cortical thickness is link to intelligence  Birth Spiral  Random gene fluctuations start tissue formation  Birth Spiral  Mapping nerve connections from brain-to-spinal cord  Birth Spiral  Infants can track others' mental state  Birth Spiral  Gene signal links cerebral palsy and autism  Birth Spiral  Atlas of the human genome using stem cells   Birth Spiral  First genetic screening for medulloblastoma   Birth Spiral  Who am I? How cells find their identity   Birth Spiral  Antiepileptic drug induces birth defects  Birth Spiral  HMGA2 gene controls body size in pigs - and humans  Birth Spiral  Women Exposed in utero to DES at High Risk for Cancer  Birth Spiral  Fast food diet slows down fertility  Birth Spiral  How Visual Experience Affects Learning  Birth Spiral  'Enhancing' the Face  Birth Spiral  Need for vitamin D may have increased breast density  Birth Spiral  Synapses control migration of neurons  May 2018   Birth Spiral  New target in Progeria Syndrome  Birth Spiral  Making sense of sight and sound  Birth Spiral  Some children predisposed to develop leukemia  Birth Spiral  Limit sugar in your diet when pregnant  Birth Spiral  Angelman syndrome is due to a defect on a single gene  Birth Spiral  The Hippocampus  Birth Spiral  Diabetes highlighted in 2 new studies  Birth Spiral  Insulin can go viral  Birth Spiral  Maternal stress creates high stress in baby  Birth Spiral  Genetic link to IBS identified in women  Birth Spiral  Why do more women have asthma than men?  Birth Spiral  Why cells act differently despite identical genes  Birth Spiral  Tracking how cell diversity occurs  Birth Spiral  Why an autistic brain can't calm down  Birth Spiral  What is asymmetric cell division?  Birth Spiral  Cell division is fundamental to life  Birth Spiral  Estimating effects of gene mutations on IQ  Birth Spiral  Watching brain cells communicate in real time  Birth Spiral  Found, switch for most common pediatric brain tumor  Birth Spiral  Mitochondrial replacement to prevent disease?   Birth Spiral  Low birthweight linked to placental protein  April 2018   Birth Spiral  Tracing individual neural signals across the brain  Birth Spiral  Imbalance between neurons disrupts development  Birth Spiral  Stress during pregnancy affects size of baby   Birth Spiral  Discovery of 'non-gene' neurodevelopment mutations  Birth Spiral  Mother's attention changes baby's genes   Birth Spiral  Creating blood stem cells from blood vessels  Birth Spiral  B cells stimulate myelin sheathing of axons  Birth Spiral  'Fixing' Duchenne muscular dystrophy cells  Birth Spiral  What makes DNA go 'loopy'?  Birth Spiral  When proteins shake hands  Birth Spiral  Omega fatty acid supplements show promise for ASD  Birth Spiral  Lopsided ear function can lead to a lopsided brain  Birth Spiral  Why babies need to move in the womb  Birth Spiral  Air pollution linked to brain alteration  Birth Spiral  Rescuing embryonic brains  Birth Spiral  Missing link connects cell growth  Birth Spiral  Creating stem cell 'twins' to study disease  Birth Spiral  Omega fatty acid supplements show promise for ASD  Birth Spiral  Paper test detects multiple diseases all at once!  Birth Spiral  Reversing type 1 diabetes  Birth Spiral  Mom's immune system shapes baby's brain  Birth Spiral  Looking for the origins of schizophrenia  March 2018   Birth Spiral  'Precision medicine' with organs-on-chips  Birth Spiral  'Brain on a chip' reveals how the brain folds  Birth Spiral  Kidney organoids test drugs  Birth Spiral  How Synchronised waves control embryo patterning  Birth Spiral  How DNA is packaged orchestrates development  Birth Spiral  Cells communicate with rhythm and beat  Birth Spiral  How quickly do cells respond?  Birth Spiral  What causes 'individual' behavior?  Birth Spiral  Egg must signal the uterus in order to implant  Birth Spiral  Mental disorders share molecular similarities  Birth Spiral  Ibuprofen early in pregnancy reduces fetal eggs  Birth Spiral  THINK BEFORE YOU DRINK!  Birth Spiral  Low carb diet risky when pregnant  Birth Spiral  Uncovering origins for brain cancer  Birth Spiral  Uncovering the origin of Huntington's disease  Birth Spiral  What makes a good egg?   Birth Spiral  A gene initiating neuron formation may lead to repair   Birth Spiral  Zika susceptibility linked to a baby's genetics   Birth Spiral  Let silenced genes speak and cure!  Birth Spiral  Mesp1 gene leads to a functioning heart  February 2018   Birth Spiral  FDA-approved drug shuts down Ewing sarcoma cells  Birth Spiral  Nerve cells can transmit electric signals after injury  Birth Spiral  'Sonic Hedgehog' alters body shape  Birth Spiral  'Hijacker' gene drives high-risk neuroblastomas  Birth Spiral  How every cell knows what and where it is  Birth Spiral  New electron microscope images DNA making protein  Birth Spiral  Chewing on the mysteries of the jaw  Birth Spiral  Watching DNA interact inside a cell  Birth Spiral  How to fold your genes  Birth Spiral  EXD2 is key to mitochondria  Birth Spiral  Memory gene goes viral  Birth Spiral  How preterm birth may impact language  Birth Spiral  Frozen or fresh, IVF embryos equal in live births  Birth Spiral  A 'muscle' cancer not really in muscle  Birth Spiral  Nucleotides - not amino acids - change gene function  Birth Spiral  Identical twins have superimilar genes!  Birth Spiral  Keeping human eggs fresh with epigenetics  Birth Spiral  Callous, unemotional traits in brains of boys  Birth Spiral  Drug developed for diabetes could treat Alzheimer's  Birth Spiral  Barcoding stem cells reveals the secrets of blood  Birth Spiral  Creating mammal tissue from simple instructions  Birth Spiral  Folic acid late in pregnancy may increase allergies  Birth Spiral  Hidden gene variation drives evolution  January 2018