In the blatocyte stage, day 5-6 of embryonic development, the embryo has an internal cell mass, the trophoectoderm and a liquid cavity called a blastocele. At this stage of development, the embryo expands. Normally, this occurs 5-6 days after fertilization, but sometimes it happens early.
By Andrea Rodrigo (embryologist), Marta Barranquero Gómez (embryologist) and Romina Packan (babygest staff).
Last Update: 12/31/2020