Menstrual cycle and implantation (2nd lesson)

Task 1: Put in order the following fragments of both parts of the menstrual cycle

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A. Uterine cycle: Near the first half of the uterine cycle, the lining of the uterus is thick enough to allow for the implantation of a fertilized egg and the onset of pregnancy. If the egg is not fertilized, the uterine lining keeps growing and is shed with the onset of the following menstrual cycle.

B. Ovarian cycle: Countless follicles in the ovaries each contain an immature egg. A hormone secreted by the pituitary gland activates the maturation of one of the follicles, which is completed half way through the cycle. Then, ovulation occurs: the mature egg leaves the ovary and is expelled to the fallopian tube.

C. Ovarian cycle: Next, the follicle becomes the corpus luteum, an endocrine structure that produces hormones during the second half of the menstrual cycle. Last, the corpus luteum regresses, completing the ovarian cycle. The following ovarian cycle will take place in the other ovary.

D. Uterine cycle: The uterine cycle starts with the shedding of the lining of the uterus, the endometrium, which produces the bleeding known as menstruation or period. After 3 to 7 days, sex hormones activate the growth of the uterine lining, which thickens and becomes richly irrigated.

Task 2: Search for the meaning of the highlighted words in task 1 and construct a glossary with them.

Task 3: Read the following text and answer the questions.

"Fertilization is the process in which an egg and a sperm combine to form a ferilized egg, the zygote. For this to take place it's usually necessary the sexual intercourse between a male and a female, and the ejaculation of semen by the penis into the cervix (the lower part of the uterus). The male gametes found in the semen will use their flagella to travel to the fallopian tubes in search of an egg.

If fertilization takes place, the zygote will descend to the uterus (which will take a week), dividing through successive mitosis into a ball of cells know as blastocyst. In the uterus, the blastocyst will attach to the endometrium, the mucous membrane of the uterus through a process know as implantation.

The implantation will trigger a hormone response in the mother preventing menstruation. The implanted blastocyst will generate the embryo and the placenta."

Questions:

- When an egg an a sperm combine, they will form the ________, which will divide through several mitosis to form the ________, which gives place to the ________  and __________ after implantation.

- The fertilization takes place in the _________ _______.

- The ________ of semen into the _______ is usually needed for the fertilization to take place.

- Menstruation is prevented by an ________ response triggered by the blastocyst implantation at the ________.

Task 4: Most people decide at some point in their lives to start a family. However, some couples have fertility problems and cannot conceive children naturally. Science has developed assisted reproductive technologies to help these couples become pregnant. One of these technologies is the in vitro fertilization (IVF).

Research this technique in internet looking for the asnwers of the following questions:

- What is in vitro fertilization?

- How is in vitro fertilization performed?

- How many embryos are transferred to the mother’s womb, and how many are implanted?

- What is done with the embryos that are not transferred?