Final answer:
Fertilization is the union of sperm and egg to form a zygote, occurring in the fallopian tubes, followed by cleavage and blastulation to form a blastocyst. The blastocyst then implants into the uterine lining approximately a week later to begin pregnancy.
Step-by-step explanation:
The process of fertilization refers to the union of a sperm and an egg, which results in the formation of a zygote. This event usually takes place in the fallopian tubes. Post-fertilization, the zygote undergoes several cell divisions, a process known as cleavage, leading to the formation of a morula and then a blastocyst. Implantation occurs when the blastocyst adheres to and embeds itself in the uterine lining, marking the commencement of pregnancy.
Germinal Stage of Human Development
The germinal stage encompasses several processes that transform an egg and sperm into a zygote and eventually an embryo. These processes include:
- Fertilization
- Cleavage
- Blastulation
- Implantation
The morula is an early stage embryo consisting of a sphere of cells. During blastulation, the morula develops a fluid-filled cavity, forming the blastocyst, which consists of two major parts: the inner cell mass that ultimately forms the embryo, and an outer layer of cells known as the trophoblast that becomes part of the placenta. Implantation takes place when the blastocyst successfully attaches to the uterine wall, approximately one week after fertilization.