Reproduction in humans
Read the following passage carefully and answer the given questions.
The female reproductive system consists of a pair of ovaries, a pair of oviducts, a uterus, a vagina, external genitalia, and a pair of mammary glands. The ovaries produce the female gamete and some steroidal hormones. Ovarian follicles in different stages of development are embedded in the stroma. The oviducts, uterus and vagina are female accessory ducts. The uterus has three layers, namely perimetrium, myometrium and endometrium. The female external genitalia includes mons pubis, labia majora, labia minora, hymen and clitoris. The mammary glands are one of the female secondary sexual characteristics. Spermatogenesis results in the formation of sperm that is transported by the male sex accessory ducts. A normal human sperm is composed of a head, neck, a middle piece and tail. The process of formation of mature female gametes is called oogenesis. The reproductive cycle of female primates is called the menstrual cycle. The menstrual cycle starts only after attaining sexual maturation. During ovulation, only one ovum is released per menstrual cycle. The cyclical changes in the ovary and the uterus during the menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones.
Which one of the following layers is necessary for the implantation of the fertilized ovum?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Endometrium
The wall of the uterus has three layers: the perimetrium on the outside, the myometrium in the middle and the endometrium on the inside.
(1) Perimetrium — Incorrect. This is the thin outer membranous layer of the uterus. The embryo does not reach it.
(2) Endometrium — Correct. This is the inner glandular layer that lines the uterine cavity. It changes during the menstrual cycle, and the blastocyst attaches to it. Progesterone keeps it ready for implantation.
(3) Myometrium — Incorrect. This is the middle thick layer of smooth muscle. It contracts strongly during childbirth. It is not the layer in which the embryo implants.
(4) Epidermal layer — Incorrect. This is not a layer of the uterus. The epidermis is the outer layer of the skin.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Menstrual Cycle – …
