Maternity Nursing Q 92

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Which of the following refers to the single cell that reproduces itself after conception?

  

     A. Chromosome

     B. Blastocyst

     C. Zygote

     D. Trophoblast

    

    

Correct Answer: C. Zygote

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The zygote is the single cell that reproduces itself after conception. It is the union of the sperm cell and the egg cell. Also known as a fertilized ovum, the zygote begins as a single cell but divides rapidly in the days following fertilization. After this two-week period of cell division, the zygote eventually becomes an embryo. If this goes well, the embryo becomes a fetus.

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Option A: The chromosome is the material that makes up the cell and is gained from each parent. Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.

Option B: The blastocyst consists of cells forming an outer trophectoderm (TE, trophoblast) layer, an inner cell mass (ICM, embryo blast), and a blastocoel (fluid-filled cavity). The inner cell mass will form the entire embryo and is the source of true embryonic stem cells capable of forming all cell types within the embryo.

Option D: In early development, the blastocyst outer trophectoderm (TE) layer will generate all the extraembryonic trophoblast cell types: cytotrophoblast, syncytiotrophoblast, trophoblastic column, and extravillous trophoblast cells. These cells have an important contribution to extra-embryonic tissues (fetal placenta and membranes) and processes of early development (adplantation, implantation, and endocrine support of pregnancy).

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