Which stage refers to the cell formed immediately after fertilization and before implantation?

Which stage refers to the cell formed immediately after fertilization and before implantation?

• A. Fetus
• B. Zygote
• C. Gestational sac
• D. Placenta

Answer: (B)

The fundamental idea here is the first cell of a new individual formed right at fertilization. When sperm and egg fuse, their genetic material combines to create a single diploid cell—the zygote. This is the immediate product of fertilization and it exists before any implantation into the uterine lining. After its formation, the zygote begins rapid cell divisions and travels toward the uterus, eventually becoming a morula and then a blastocyst that will implant. In contrast, a fetus is a much later developmental stage, the gestational sac is the early surrounding structure around the embryo/blastocyst after implantation, and the placenta forms as the pregnancy progresses to nourish the developing embryo. So the cell formed right after fertilization and before implantation is the zygote.

The fundamental idea here is the first cell of a new individual formed right at fertilization. When sperm and egg fuse, their genetic material combines to create a single diploid cell—the zygote. This is the immediate product of fertilization and it exists before any implantation into the uterine lining. After its formation, the zygote begins rapid cell divisions and travels toward the uterus, eventually becoming a morula and then a blastocyst that will implant. In contrast, a fetus is a much later developmental stage, the gestational sac is the early surrounding structure around the embryo/blastocyst after implantation, and the placenta forms as the pregnancy progresses to nourish the developing embryo. So the cell formed right after fertilization and before implantation is the zygote.