The research was carried out to discribe day 3 and day 5(blastocyst) embryo's morphological features that cultured in-vitro and morphological relations between them. This research will be the basic for culturing the embryo in vitro to the day 5 stage (blastocyst). Result: a good quality day 3 embryo have the size of 153,3 + or - 7,4 um in diameter with 8-10 blastomeres and ZP's thickness is 14,67 + or - 2,41 um, a good quality blastocyst have: expanded blastocoel
ICM is prominent, easily discernible, with many cells that are compacted together tightly
TE with many cells forms a cohesive epithelium. There is a morphological relationship between day 3 and day 5 embryos that cultured in-vitro.