Reproductive Technology. Chapter 21

Transcription

1 Reproductive Technology Chapter 21

2 Assisted Reproduction When a couple is sub-fertile or infertile they may need Assisted Reproduction to become pregnant: Replace source of gametes Sperm, oocyte or zygote donors Aid in the fertilization process Replace the uterus Surrogate mothers Treat cause of infertility

3 Infertility Clinically defined as inability to conceive after more than one year of intercourse without contraception World Health Organization Defines sub-fertility as diminished ability to conceive Infertility as complete inability to ever conceive Personally Means changing your entire life plan

4 Infertility Statistics Affects about 1 in 6 couples in USA Cause can be identified in about 85% of cases Can be treated successfully in about % of couples Problem in female 50% Problem in male 30% Problem in both partners 20%

5 Male Infertility Problems: Oligospermia low sperm count Caused by: hormones, environment, physical Poor sperm quality Motility sperm can t swim Abnormality sperm are abnormally shaped Antibodies against own sperm Autoimmune disorder

6 Genetics of Male Infertility Oligospermia low sperm count Genes: hormones, Y chromosome abnormalities, testicular/prostrate development Environment: drugs, toxins, heat (kills) Poor sperm quality Genes: hormones, enzymes to harness energy Environment: drugs, toxins, heat (mutates) Antibodies against own sperm Genes: Immune system malfunctioning

7 Treatment of Male Infertility Primary change environment Avoid heat, drugs, toxins Timing intercourse Secondary correct hormone levels, surgery corrects physical problems, immune suppressants Final Assisted Reproduction Technologies

8 Female Infertility Problems: Irregular/malfunctioning ovulation Hormone imbalance, malfunctioning or absent ovaries or tubes Physical blockage Fibroids or Endometriosis Blocked/abnormal Fallopian tubes Vaginal secretions Hormones or certain diseases

9 Female Infertility

10 Genetics of Female Infertility Irregular/malfunctioning ovulation Genes: Hormones, thyroid, pituitary problems Environment: Birth control, stress Physical blockage Genes: Cancer, developmental defect Environment: Cancer or infections Vaginal secretions Genes: Hormones, mucus disorders, immune

11 Treatment of Female Infertility Primary change environment Timing intercourse - checking for ovulation Decrease stress, diet, exercise, etc Secondary correct hormone levels, surgery to correct physical problems Final Assisted Reproduction Technologies More often necessary for female infertility

12 Infertility Testing Couple seek testing after trying for more than one year Tests: Semen Analysis (male) Hormone levels checked (female) Physical exams (both) Hysterosalpingogram (HSG; female) Endometrial Biopsy (female) Post coital exam (done on female)

13 Assisted Reproductive Technologies (ART) Donating gametes Surrogate mothers Helping bring gametes together (fertilization) Putting zygote in correct place Preimplantation screening

14 Donating gametes Sperm donation: For Lesbian couple or male infertility Sperm can be inseminated into uterus or cervix (artificial insemination) Or sperm can be mixed with oocyte and zygote implanted Oocyte donation: Mixed with sperm and implanted as zygote More costly and harder to come by than semen

15 Surrogate Mothers Book defines as donating uterus What else? Also time, energy, effort, hormones, blood, diet, health care Surrogate mothers: Inseminated with father s semen, using her own oocytes Or may be implanted with a zygote from couple s gametes Legal rights of surrogate mothers vary by state and country

16 Helping Fertilization IVF in vitro fertilization Sperm and oocyte are mixed in Petri dish Embryo at 8 or 16 cell stage implanted into uterus ICSI intracytoplasmic sperm injection Sperm actually microinjected into oocyte Then embryo implanted into uterus Important when father has low sperm count or large number of abnormal sperm

17 in vitro Fertilization (IVF) Problem is that egg and sperm can t meet: Blocked tubes or abnormal structures Not enough healthy sperm Put sperm and egg together in dish and then implant early embryo into uterus Costs $5,000 to 15,000 each try Success rate ~ 30% Children have ~ twice rate of birth defects

18 ICSI IVF where sperm is injected into oocyte

19 Improving IVF s chances: Use ICSI Implanting more than one embryo What is the problem there? Implant embryos at later stage in development (blastocysts) Culturing zygote with helper cells that normally surround embryo Screening embryos for chromosomal abnormalities

20 Helping Fertilization ZIFT zygote intrafallopian transfer Same as IVF only implanted into fallopian tube rather than uterus Less successful than IVF (~23%) GIFT gamete intrafallopian transfer Deposit the sperm directly into fallopian tubes Or deposit sperm and oocytes (mother s or donor s) into fallopian tubes Like IVF that happens internally (~26%)

21 Preimplantation Screening Screening for genetic disorders BEFORE pregnancy begins: One cell of 8 cell embryo is removed Single cell is karyotyped and probed with FISH for specific genetic disorders Preimplantation Genetic Diagnosis (PGD) Only genetically healthy embryo is implanted (IVF) ~ 29% success rate

22 PGD Screen for: Large chromosomal abnormalities Rare Mendelian Disorders Boys with X-linked disorders PGD often done on IVF embryos to screen for chromosomal abnormalities commonly associated with IVF procedure Weigh risk of disease vs. IVF not working Who could help make this decision?

23 Spares Every time IVF is done more embryos are made than are used ~ 500,000 embryos are currently in deep freeze in USA today from IVF Choices: Research example: stem cells Donation to infertile couple Discard them Who should make this choice?

24 Adoption Domestic Adoptions: $5,000 to $40,000 Must pass stringent screening process: Salary, housing, marital situation, criminal records International Adoptions: $7,000 to $30,000 Different screening processes Foster Care Adoptions: Free or subsidized older and abused children

25 Lets Talk about Ethics Get into groups of four Discuss what you think of each of these ART situations as if you were: 1. One member of couple in question 2. Politician (pro life and pro ART) 3. Insurance company representative 4. Genetic counselor

26 Ethics of ART 1. A young, married couple is infertile. They have basically no insurance because he works as a free lance consultant and she works two part time jobs. Although they own a home and can afford to raise a child they can not afford to undergo the testing or treatments for their infertility. Neither can they afford adoption.

27 Ethics of ART 2. A lesbian couple has one child. The mother was inseminated from a sperm donor and carried the baby produced from her own oocyte. They happily raise the child together for 6 years, until the mother suddenly finds religion and decides that homosexuality is wrong. When they break up the mother wants the child but so does her ex.

28 Ethics of ART 3. An infertile couple has insurance that covers IVF but they don t believe in using ART because of their religion. They would rather adopt, but their insurance doesn t cover adoption (most don t) and they can t afford it.

29 Ethics of ART 4. An infertile couple uses Clomid (a drug that stimulates ovulation) to become pregnant. Suddenly they find themselves pregnant with 6 embryos. They don t believe in selective reduction so they are going to try to carry all 6 babies to term. Their doctor knows that the babies won t be healthy. The father concurrently loses his job, so now they have no insurance.

30 Ethics of ART 5. A couple wants to use PGD to make sure they have a girl. What would you think if: a) They have 5 boys and want a girl b) They live in China and can only have one child c) They know the mother carries an X linked disease

31 Next Class: Read Chapter 22 Homework Chapter 21 Problems; Review: 1, 2, 9 Applied: 1, 4, 5, 6, 10, 11