Implantation site 2x3mm. The maternal tissue is invaded by trophoblast (primary) giant cells and the ectoplacental cone is invaded by maternal blood. Differentiation of the egg cylinder into embryonic and extraembryonic regions and the formation of the proamniotic cavity. Reichert's membrane, which is non-cellular and secreted by the distal endoderm first appears.  

6 dpc (range 5-6.5) 
Witschi Stage 10-11 (rat - stage table)
Carnegie - Stage 5 (human - stage table)
Virtual Human Embryo - Stage 5

Scale bar in microns.