Development, migration, and fertilization of an oocyte
During the ovulation, the mature (secondary) oocyte exits the follicle (blue) and the ovary (rosy rounded structure). Thready extensions (fimbria) of the uterine tube catch the oocyte (1. oocyte from the left), so that it can make its way towards the uterus via the tube. When fertilized (2. oocyte from the left), this oocyte begins with the mitotic cell division. It passes through different stages until it`s grown up to a grape-shaped pile of cells (morula, 5. & 6. oocyte from the left). When a hollow cavity has developed inside the pile of cells, it`s called blastomere. Its inner layer is the embyroblast, out of which the embryo develops. When the blastocyst settles into the endometrium of the uterus, it`s called nidation.