Blastocyst embedding into the uterine wall. Animation of the early stages of pregnancy, with the blastocyst (formed around 1 day after fertilisation) in the uterus. The blastocyst embeds into the endometrium, the wall of the uterus, and begins a process known as gastrulation. The entire process of embedding (implantation) takes 11-12 days from fertilisation. The blastocyst consists of an outer layer (the trophoblast), an inner cavity (the blastocoele), and the inner cell mass (which will later form the embryo). During gastrulation, the blastocyst reorganises into the ectoderm, mesoderm, and endoderm germ layers. This animation is part of a sequence illustrating the female reproductive system, ovulation, fertilisation and pregnancy. For the conclusion of this animation, see clip K005/5513. |