Pre-Streak (PS): Advanced egg-cylinder stage with the first evidence of of an embryonic axis. There is clear morphological distinction between the embryonic and extraembryonic ectoderm. The ectoplacental cone is further invaded by maternal blood and the original lumen of the uterine crypt has disappeared.

Early Streak (ES): Late in this stage gastrulation begins, producing the first mesodermal cells.

6.5 dpc (range 6.25-7.25) 
Downs & Davies  PS - ES:  prestreak to early streak 

Witschi Stage 11 (rat - stage table)
Carnegie - Stage 6-7 (human - stage table)
Virtual Human Embryo - Stage 6

Scale bar in microns.