Question

Which one of the following is the most likely root cause for menstruation not taking place at regular cycling in human females?
A. Maintenance of the hypertrophical endometrial lining.
B. Maintenance of high concentration of sex hormones in the bloodstream.
C. Retention of well-developed corpus luteum.
D. Fertilisation of the ovum.

Answer 1

Hint:The term "menstrual cycle" refers to the regular cycles of occurrences that occur during a woman's reproductive years. At the time of ovulation, an ovary's Graafian follicle releases an ovum into the abdominal cavity. The absence of a menstrual cycle can be an indication of pregnancy.

Step by step solution:
If pregnancy does not develop after ovulation, the thicker endometrium is shed or desquamated. Along with blood and tissue fluid, this desquamated endometrium is ejected through the vagina. Menstruation, also known as menstrual bleeding, is the process of the uterine lining being shed and leaving the body accompanied by blood and fluid. The ovary's production of oestrogen and progesterone abruptly decreases at the end of the cycle. Menstruation is brought on by these two hormones' reduced levels.
Because the anterior pituitary's ability to secrete FSH and LH is suppressed after the ovum has been fertilised, no follicular alterations take place in the ovary and no ovulation takes place. To support the pregnancy, the corpus luteum expands and secretes a significant amount of progesterone and a small amount of oestrogen. Endometrium does not shed when progesterone secretion is increased and oestrogen secretion is minimal.

So, option D is correct.

Note: The ovum is at the secondary oocyte stage and has a haploid number of chromosomes when it is discharged into the abdominal cavity following ovulation. The ovum, which is in the secondary oocyte stage at the time of fertilisation, immediately divides into a mature ovum and a second polar body. Expulsion of the second polar body occurs. When an ovum reaches maturity, its nucleus changes into a female pronucleus with 23 chromosomes, including 22 autosomes and one X chromosome that is specific to sex.