Question

What changes are observed in the uterus, if fertilization does not occur?
(A) Lining of uterus becomes more thick
(B) Lining of uterus becomes more spongy
(C) Lining of the uterus slowly breaks and comes out through the vagina as blood and mucus
(D) Lining of uterus becomes more vascular

Answer 1

The process of fertilization happens when a sperm successfully meets an ovum within the Fallopian tube. Once it takes place, this newly fertilized cell is called a zygote. From here, the fused cell zygote will move down the Fallopian tube and into the uterus.
It then burrows into the uterus lining. This is often called implantation. When it implants, it’s called a blastocyst. The uterus lining feeds the blastocyst, which eventually grows into a fetus. If the egg doesn't get fertilized by the sperm all the above stated process won't occur and therefore the uterus which was prepared for the implantation of embryo will degenerate.

Complete answer:
Option A (lining of uterus becomes thicker): monthly before ovulation the lining of uterus becomes thick this is the action of progesterone to supply a protective lining for the embryo after fertilization.
Option A isn't correct.
Option B (lining of uterus becomes spongier): monthly before ovulation the lining of uterus becomes thick thanks to the action of progesterone to supply a protective lining for the event of embryo after fertilization.
Option B isn't correct.
Option C (Lining of the uterus slowly breaks and comes out through the vagina as blood and mucus): If fertilization doesn't occur within the uterus, the endocrine gland will involute and there'll be a drop by the hormone levels, which can cause the uterus to shed its lining and egg within the process called menstruation, where there's blood and uterine secretions are removed through the vagina.
Option C is correct.
Option D (lining of the uterus becomes more vascular): During pregnancy (after fertilization) the glands and blood vessels within the endometrium further increase in size and number. These vascular spaces then fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus.
Option D isn't correct.

So, the correct answer is “Option C”.

Note:

1. All menstrual cycles don't last $28$ days.
2. The timing of menstruation depends on that of ovulation.
3. Periods are often irregular thanks to stress or illness.
4. Fluctuations in weight can affect your period.
5. Abnormal bleeding can indicate underlying serious health issues.
6. Irregular periods can often be treated with contraception pills or other hormonal treatments.