Interactive CS20 Embryo Model


The model is high resolution. Please allow time for it to load.

        Key to anatomical regions

  • Central nervous system
  • Optic vesicle
  • Otic vesicle
  • Dorsal root ganglia
  • Heart
  • Liver
  • Trachea
  • Lungs
  • Gastrointestinal tract

Movies of CS20 embryos


The movies below show volume renders of OPT models. Images of unstained embryos were captured using autofluorescence with a FITC filter.


N382 46XX
N529 46XY


The movies below show volume renders of High Resolution Episcopic Microscopy (HREM) models. Other HREM models can be found here.

N913 46XX
1645 46XX





Painted Anatomical Regions


The movie below shows anatomical domains defined in the N382 model. The domains have been manually defined in the OPT model using specialised software and then visualised using commercial rendering packages.

The various domains are: neural tube - orange; heart - red; liver - dark green; optic vesicle - dark blue; otic vesicle - yellow; dorsal root ganglia - cyan.


N382 46XX





Carnegie Stage 20 Definition



A 3D model of a human embryo, Carnegie stage 20


Age is approximately 49 postovulatory days

Length is approximately 18 - 23mm

External Features Include: the upper limbs have become slightly bent at the elbows; hands have short, stubby fingers and are still far apart, a delicate fringe-like vascular plexus appears in the superficial tissue of the head and the edge of the plexus is approximately halfway between ear-eye level and the vertex of the head.

O'Rahilly R and Muller F [1987] Developmental Stages in Human Embryos. Carnegie Institute, Washington, Publication no. 637, and O'Rahilly R, Müller F (2010) Developmental stages in human embryos: revised and new measurements. Cells Tissues Organs. 192:73-84. PMID: 20185898.