1. Visualization of atypical hatching of a human blastocyst in vitro forming two identical embryos 
Barry Behr, Ph.D., H.C.L.D., Amin A Milki, M.D. 
Fertility and Sterility 
Volume 80, Issue 6, Pages (December 2003)
DOI: /j.fertnstert

2. Figure 1
Hatching day 5 blastocyst. Two trophoblast populations sharing an inner cell mass can be seen.
Behr. Atypical blastocyst hatching. Fertil Steril 2003.
Fertility and Sterility  , DOI: ( /j.fertnstert )

3. Figure 2
Two hatched blastocysts late on day 5 originating from a single blastocyst.
Behr. Atypical blastocyst hatching. Fertil Steril 2003.
Fertility and Sterility  , DOI: ( /j.fertnstert )