This animation begins with the 14th day of the menstrual cycle immediately after fertilization. The term "cleavage" is defined. The structure of the uterus shows the endometrium at the end of the proliferative phase, and the ovary with the just ovulated tertiary follicle, i.e. future corpus luteum. In the ampulla of the uterine tube, the zygote is surrounded by a mass of spermatozoa. All details are shown under low magnification. Each image also presents a calendar of the menstrual cycle.

To enable simultaneous observation of zygote segmentation and transport along the uterine tube, another zygote is shown in parallel under low magnification.

The animation follows the cleavage of the zygote and its move within the oviduct from 1 day of age (2 blastomeres), 2 days of age (4 blastomeres), 2.5 days of age (8 blastomeres), 3 days of age (16 blastomeres, i.e. morula), 4 days of age (58-64 blastomeres = advanced morula), 4.5 days of age (65-106 blastomeres, i.e. early blastocyst) and 5 days of age (106 + blastomeres, i.e. advanced blastocyst). This stage shows the breakdown of the zona pellucida and the hatching of the blastocyst. The last sequence illustrates a 6-day-old blastocyst (day 20 of the menstrual cycle) with a distinct trophoblast and embryoblast.

The animation also shows the effects of progesterone and relaxin on the endometrium and the peristaltic contractions of the uterus and uterine tube.

(This animation is essential for students of medicine, stomatology and biology; it is also recommended for students of veterinary medicine, departments or clinics of obstetrics and gynecology, and schools for midwives).