Interactive 3D PDF of Carnegie Stage 10


The interactive PDF below has been very kindly provided by Dr. Jill PJM Hikspoors, Prof. Wouter H Lamers,
Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands

Publication: 10.1038/s42003-022-03153-x

Supplementary tables

*Important* Although some web browsers will allow PDFs to be viewed online, the file must be downloaded and saved to a computer to enable the interactive options.


Right-sided view
Right dorsal view: Start of the closure of the neural plate at the level of somite 4
Ventral view: Single endocardial channel between paired venous and arterial channels
Right ventral view: Loop wire shows the pattern of the single endocardial channel
Dorsal view: Dorsally the myocardial wall is open (dorsal mesocardium)


Carnegie Stage 10

It is within this stage, when ~28 days have passed since fertilization. The neural plate is flanked by 8 somites. It is transforming into a neural tube at the level of somite 4, representing the future junction of the head and neck. The endoderm, shown in grey, is still continuous at its periphery with the yolk sac, which is shown in darker grey.

Within at most 2 days, the heart has transformed into a single endocardial conduit extending between still paired venous and arterial vessels. The single channel has the embryonic left ventricle as its caudal, and the embryonic right ventricle as its cranial component. The umbilical vein, which occupies the boundary of embryonic disk and amnion, and the vitelline plexus, which is situated on the yolk sac, merge at the level of the 4th somite to form the hepatocardiac channels. These channels, in turn, join the systemic venous inflows to the heart. At this stage, both arms of the cardiac inflow tract are transversely oriented vessels, merging in the midline. This site of union represents the caudal continuity between the first and second heart fields, and corresponds with the future atrioventricular junction. It is not yet possible anatomically to identify specific venous tributaries, but the primordia of the atrial chambers are visible. Cardiac jelly forms a thick cuff around the single endocardial tube, while the outer myocardial wall surrounds the jelly as a cloak, which is open dorsally as the dorsal mesocardium. The dorsal mesocardium connects the heart with the overlying pharyngeal floor, while the transverse septum supports the embryonic ventricle caudally.

The lumen of the heart resembles that of an hourglass. At the narrowest part of the hourglass, the dorsal mesocardium has disappeared. At this site, the transverse pericardial sinus, identifiable by the interruption of the dorsal mesocardium, marks the transition from the descending, or inlet, to the ascending or outlet limb of the forming cardiac loop. This junction between the embryonic left and right ventricles will eventually be the location of the interventricular foramen. It is at this position, furthermore, that the heart tube bends rightward and, in particular in its cranial part, ventrally.

The looping of the heart brings out the separation of the second heart field into caudal and cranial portions. In mice, the caudal second heart field gives rise to both atrial chambers at CS10-11, and the systemic venous sinus at CS12 (Table 1). At CS10, the cranial second heart field gives rise to the embryonic right ventricle proximally, while the distal portion becomes the myocardial outflow tract at CS11 (Table 1). In mice, the embryonic right ventricle originates from myogenic cells in the second heart field, which also give rise to the muscles of the 1st pharyngeal arch, whereas the outflow tract is covered by cardiomyocytes, which originate in similar fashion from myogenic cells in the 2nd pharyngeal arch.

The outflow tract, at the arterial pole, continues extrapericardially as the paired ventral aortas, which extend parallel to the pharyngeal floor in cranial direction. They then pass perpendicularly to the pharynx, in front of its widening part, which will give rise eventually to the pharyngeal pouches, to join both dorsal aortas. Ventral aortas are found in embryos of all higher vertebrates, including human embryos during CS10 and CS11. The cranial boundary of the cardiac jelly coincides with the transition of the outflow tract to the ventral aortas. The dorsal aortas course caudally between the dorsolateral wall of the pharynx and the somites, breaking into a plexus where somites are forming. By this stage, the roots of the first pair of intersegmental arteries can be recognized between somites #1 and #2.


How to download and view the PDF



Click an image to download a 3D-PDF. The file must be saved to a computer to enable the interactive options. The 3D-PDFs can be opened on any computer as long as Adobe PDF or equivalent reader is installed.

A 3D-PDF becomes activated by “clicking” with the mouse on the reconstruction.
A toolbar appears at the top of the screen that includes the option “model tree”. The model tree displays a material list of structures in the upper box, and preset viewing options (cameras) in the lower box. The sequence of items corresponds to that in Supplemental Table 3 of the publication.

The list of visible structures can be modified by marking or unmarking a structure.

To manipulate the reconstruction, press the left mouse button to rotate it, the scroll button to zoom in or out, and the left and right mouse buttons simultaneously to move the embryo across the screen.

A structure can be rendered transparent by selecting that option from the drop-down menu after selecting the structure with the right mouse button.

To inspect a combination of structures, one is advised to build up the composition, beginning with a familiar component, such as a lumen, rather than deleting non-relevant structures one-by-one from a completely reconstructed specimen.

The slicer button in the toolbar allows making cross sections. The plane of section can be adjusted with the offset and tilt options.

The “loop wires” in Supplemental Figures 3-6 of the publication, which are drawn through the center of the endocardial heart tube, emphasize the changing shape of the heart loop during CS10-13.

The side length of the scale cubes is 200 μm.

The preset views correspond to the images shown in Figures 1-10 of the publication.

Note that items that are visible in these views can be altered by marking or unmarking a structure in the model tree.