The function of copper T is to prevent (A) Fertilization (B) Egg maturation (C) Ovulation (D) Implantation of blastocyst
Hint: Fertilization is the fusion of male and female gametes i.e. egg from female and sperm from male) usually taking place in ampulla of the fallopian tube, which results in the formation of new cell called as zygote.
Complete answer: Fertilization occurs in human beings inside the ampullary – isthmic junction of the oviduct. The egg released from the mature Graafian follicle of an ovary (ovulation) is received by nearly fallopian funnel and sent into the fallopian tube by movements of fimbriae and their cilia. It is in the secondary oocyte with the second meiotic division in progress. The oocyte can live for 72 hours but can be fertilized only during the first 24 hours of this period. Ovum takes 12-24 hours to reach the site of fertilization. Male discharges semen high up in the female’s vagina close to the cervix during coitus (copulation). This is called insemination. From the vagina the sperms travel up the uterus but only a few thousand find their way into the openings of the fallopian tubes. Primarily, contractions of the uterus and fallopian tubes assist in sperm movement but later on they move by their own motility. Sperms swim in the fluid medium at the rate of 1.5 to 3 mm per minute to reach the site. The leucocytes of the vaginal epithelium engulf millions of sperms. The effective and popular method to prevent fertilization is the use of intrauterine devices (IUDs). These devices are inserted by doctors or expert nurses in the uterus through vagina. These intra uterine devices are presentable as the non- medicated IUDs (eg, lippes loop), Copper releasing IUDs (CuT, Cu7, Multiload 375) and the hormone releasing IUDs (Progestasert, LNG-20). IUDs increase phagocytosis of sperms within the uterus and the cu ions released suppress sperm motility and the fertilizing capacity of sperms. The hormone releasing IUDs, in addition , make the uterus unsuitable for implantation and the cervix hostile to the sperms. IUDs are ideal contraceptives for the females who want to delay pregnancy and/or space children. Egg maturation is also called oocyte maturation and refers to a release of meiotic arrest that allows oocytes to prophase I to metaphase II of meiosis. An oocyte is an immature egg. Oocytes develop to maturity from within a follicle. These follicles are found in the outside layer of the ovaries. During each reproductive cycle, several follicles begin to develop. Ovulation is the release of a mature egg from the ovaries, which happens every month, after releasing the egg it moves down the fallopian tube, where fertilization by a sperm cell may occur. Implantation occurs in the blastocyst stage after about a week of fertilization. Zona pellucida dissolves. The exposed trophoblast or tropho-ectoderm comes in contact with endometrial lining in the region of embryonic pole. Trophoblast cells secrete lytic enzymes, cause breakdown of some endometrial cells, absorb nourishment and divide themselves to form villi. Villi penetrate endometrium for fixation and absorption of nourishment. The attachment of a young embryo or blastocyst to the endometrium of the uterus is called implantation.
So, the correct answer is option A i.e. Fertilization.
Note: Pills have to be taken daily for a period of 21 days starting preferably within the first five days of menstrual cycle. After a gap of 7 days it has to be repeated in the same pattern till the female desires to prevent conception. They inhibit ovulation and implantation as well as alter the quality of cervical mucus to prevent/ retard entry of sperms.