Miscellaneous+NLL

Miscellaneous Reproduction Topics

(1) What does IVF stand for? What does it treat? How does the doctor get the eggs? Where are the embryo’s made and when are they implanted? Where are they implanted? (P.334) IVF stands for In Vitro Fertilization. IVF is used to spot follicles in the ovaries that hold immature eggs. The latest method is to forgo the administration of fertility drugs and retrieve immature eggs by using a needle. The immature eggs are bought to maturity in glassware, and then concentrated sperm are added. After about two to four days, the embryos are ready to be transferred to the uterus of the woman, who is now in the secretory phase of her uterine cycle. If desired, the embryos can be tested for genetic disease, and only those found to be free of disease will be used. If implantation is successful, development is normal and continues to term.

(2) Embryos that are not implanted are frozen? What can happen to frozen embryos? (P.335) In spite of potential trials, thousands of people undergo fertility treatment every year. Its popularity has brought a number of ethical issues to light. For example, the estimated high number of stored frozen embryos has generated debate about their fate, complicated by the fact that the long-term viability of frozen embryos is not well understood. Scientist may worry that embryos donated to other couples are ones that were already screened out from one implantation, and not be likely to survive. Some religious groups strongly oppose destruction of these embryos of their use in research. Patients for whom the embryos were created generally feel that they should have sole rights to make decisions about their fate. However, a fertility clinic may no longer be receiving monetary compensation for the storage of frozen embryos and unable to contact the couple whom they were produced.

(3) What is an ectopic pregnancy? (p. 357) Implantation of the embryo in a location other than the uterus, most often in an oviduct.

(4) Briefly describe how cloning is done. (p. 362) A donor 2n nucleus is substituted for the nucleus of an egg; a stimulus is applied that triggers cell division, and the resulting embryo is implanted into a surrogate mother where it develops to term. Donor nucleus contains DNA→remove and discard egg nucleus→fuse egg with donated nucleus→electric shock triggers cell divisions→embryo begins to develop in vitro→embryo is implanted surrogate mother→clone is born.

(5) What are some the problems that have developed in cloned animals? (p. 362)

(6) What is the difference between reproductive cloning and therapeutic cloning? What are the pros and cons of each? (p. 362) Reproductive cloning is genetically identical to the original individual. Therapeutic cloning is used to create mature cells of various cell types. Also, used to learn about specialization of cells and province cells and tissue to treat human illness.

(7) When can you tell if an embryo is a boy or girl? (p. 364) The sex of an individual is determined at the moment of fertilization. Males have a pair of chromosomes designated as X and Y, and females have two X chromosomes.

(8) Describe two causes of cases where a person is XY (male) but looks and acts female. (p. 365) In individuals with the XY chromosome female syndrome, a piece of the Y chromosome is missing. In individuals with the XX male syndrome, this same small piece is present on an X chromosome. The piece of a Y chromosome that causes male genitals to develop is called the SRY (sex determining region of the Y) gene. The SRY gene causes testes to form, and then the testes secrete these hormones: (1) Testosterone stimulates development of the epididymides, vasa deferentia, seminal vesicles, and ejaculatory duct. (2) Anti-Mullerian hormone prevents further development of female structures, and instead causes them to degenerate.

(9) What is true hermaphroditism? (p. 365) True hermaphroditism in which a person has both ovarian and testicular tissue is rare. However, it is estimated that about 1% of the population may have male pseudohermaphroditism. The individual has testes but appears to be a normal female until puberty. The testes never produce testosterone or dihydrotestosterone.

(10) What is stage 3 of birth? What happens? (p. 369) The placenta or afterbirth is delivered during the third stage of parturition. About 15 minutes after delivery of the baby, uterine muscular contractions shrink the uterus and dislodge the placenta. The placenta then is expelled into the vagina. As soon as the placenta and its membranes are delivered, the third stage of parturition is complete.