D1: Oesophagus/stomach junction. R lung bud prominent. (L lung bud is more cranial, therefore R primary bronchus is more vertical than the left - cf. Gross Anatomy). note ventral anchoring of pulmonary mesenchyme to the septum transversum, in which is also embedded the sinus venous. Coelomic canals.
D3: Rotation of stomach (seen from above) to R side. Note change in outline of coelomic canals due to presence of liver. Lesser sac. Note thick mesothelium lining the coelom along Ledge of stomach, the primordium of the spleen and greater omentum along greater curvature. Liver embedded in septum transversum (ventral border of septum transversum contributes to diaphragm).
D3: Spinal cord has enlarged ventral horns (motor neurons).
Dl-D3: Dermatome, myotome, sclerotome. Dorsal root ganglia. Notochord. Note the dorsal segmental branches of the dorsal aortae and the inferior cardinal veins. In the walls of the neural tube, note the alar and basal laminae of cells, sulcus limitans.
The Carnegie stage 13/14 Pig Embryo is 6mm in size and approximately equal to day 42 Human Embryo. Use the serial images to identify internal features and relationships that exist within the embryo at this stage. Then compare these images with the external appearance of the embryo at this stage and the later internal features of the stage 22 embryo.
Note that the nomenclature "stage 13/14" is not an actual Carnegie stage but indicates that the embryo stage lies between or has features of both stage 13 and stage 14 embryos.
Levels shown on whole embryo are only approximate.
Note that not all embryo features are labelled.
Hint: clicking on each section image above will also step you through the whole embryo in sequence.