Question

In human beings, after fertilization, the structure which gets embedded in the wall of the uterus is

• A. Ovum
• B. Embryo
• C. Blastocyst
• D. Zygote

Answer 1

The correct option is C

Blastocyst

The correct option is C.

The explanation of the correct option:

1. A cluster of dividing cells called a blastocyst is produced by a fertilized egg.
2. It's an embryo in its early stages.
3. A blastocyst is merely one of several steps that lead to pregnancy.
4. A blastocyst develops about five to six days after a sperm fertilizes an egg, a blastocyst.
5. The blastocyst's cell layers divide and separate.
6. They eventually develop into the structures that safeguard and support the growing fetus (unborn baby).
7. A blastocyst develops from the morula once it enters the uterus.
8. The blastocyst subsequently undergoes implantation, in which it burrows into the uterine lining.
9. Three stages make up the process of implantation: (a) the blastocyst makes contact with the endometrium at the intended location (apposition); (b) the blastocyst's trophoblast cells adhere to the receptive endometrial epithelium, and (c) the invasive trophoblast cells cross the endometrial epithelial basement membrane and invade.
   

Explanations of the incorrect options:

Option A:

1. A single cell that is discharged from one of the female reproductive organs, the ovaries, and is capable of developing into a new organism when fertilized (combined) with a sperm cell is called an ova, or plural ova, in human physiology.
2. The ovum's role is to carry the female's contribution to the chromosomal set and to provide the ideal conditions for sperm fertilization.
3. Additionally, ova supplies nutrition to the developing embryo up until it enters the uterus and the placenta takes over.

Option B:

1. The blastocyst grows into an embryo linked to a placenta and surrounded by fluid-filled membranes inside the uterus, where it implants into the uterine wall.
2. The uterus is made ready for a fertilized egg to be implanted by progesterone.
3. The fertilized egg (embryo), which results from sexual activity and a man's sperm fertilizing the egg (a process known as conception), will pass through the fallopian tube and implant in the uterus.

Option D:

1. A zygote is an egg cell that has been fertilized as a result of the pairing of a female gamete (egg, or ovum) with a male gamete (sperm).
2. In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell divides into smaller cells.
3. The uterus receives the egg.
4. It exits the uterus through the vagina if it is not fertilized, and the endometrial lining is removed throughout our menstrual cycle.
5. An egg becomes fertilized when it fuses with a male sperm cell and adheres to the endometrium.
6. The uterus's thick wall shields the developing fetus throughout pregnancy.
7. Following fertilization, a zygote is created.
8. The zygote begins to move in the direction of the uterus, where beginning development occurs.
9. On the third day of the morula stage, the zygote enters the uterus and grows into a blastocyst that implants in the uterine wall.

Final answer: In human beings, after fertilization, the structure that gets embedded in the wall of the uterus is called a blastocyst.