Match List - I with List - II.

Choose the correct answer from the options given below:

(A)-(IV), (B)-(I), (C)-(II), (D)-(III)

The correct answer is Option (4) → (A)-(IV), (B)-(I), (C)-(II), (D)-(III)

A. Fertilization results in the formation of a diploid zygote. As zygote moves through the uterus, mitotic divisions occur in the zygote that results in the formation of blastomeres. Embryo with 16 celled-stage is known as a morula.

B. Stem cells are cells that have the remarkable ability to develop into different types of cells in the body. They are known for their potency to give rise to all the tissues and organs. Stem cells serve as the body's raw materials, from which all other cells with specialized functions are generated.

C. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex. This triggers release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates further secretion of oxytocin. The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions. This leads to expulsion of the baby out of the uterus through the birth canal – parturition.

D. The ovulation (ovulatory phase) is followed by the luteal phase during which the remaining parts of the Graafian follicle transform as the corpus luteum. The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy.