Final answer:
Fertilization occurs in the Fallopian tube after the oocyte leaves the ovary, leading to the formation of a zygote which implants in the uterus after about one week. This marks the start of the germinal stage of prenatal development, followed by the embryonic and fetal stages.
Step-by-step explanation:
Fertilization is the process in which a sperm and an oocyte (egg) combine and their nuclei fuse to form a zygote. In humans, this event typically occurs in the Fallopian tube soon after the oocyte leaves the ovary, which can be hours to a day post-ovulation. Following successful fertilization, the zygote travels towards the uterus and, after approximately one week, undergoes implantation. Implantation marks the beginning of the germinal stage of development, which lasts a total of eight to nine days. During this time, the initial cell divisions take place, resulting in the formation of the morula and eventually the blastocyst, before the blastocyst implants onto the endometrium of the uterus.
Key Stages of Prenatal Development
There are three key stages of prenatal development: germinal, embryonic, and fetal stages. The germinal stage is the first two weeks post-fertilization, leading up to implantation. The embryonic stage then follows, characterized by cell division, migration, and differentiation, setting the groundwork for organ formation. Eventually, the fetal stage encompasses the continued growth and maturation of all organ systems until birth.