FINAL LEC 4: Reproductive Technologies Flashcards
-When the savior child is born, its umbilical cord blood can be saved as a source of stem cells for the patient inneed ofa transplant
➔ First case: Led to the birth of_____
SAVIOR SIBLING, Adam Nash
Inability to conceive a child after a year of frequent sexual intercoursewithout the use of contraceptives
INFERTILITY
➔ Delay in conceiving
➔ The possibility of conceiving naturally exists, but exists, but takes longer than average
SUBFERTILITY
➔ Start at menopause (_____), only a thousand or so oocytes remain inher ovaries
➔ Incidence of pregnancy-related problems rises with maternal age, including chromosomal anomalies, fetal deaths, premature births, & low birth-weight babies
AS WOMAN AGES, FERTILITY DECLINES, Age 51
➔ Are at increased risk of having children who develop autism& schizophrenia
➔ Spermmotility declines with age of the man
OLDER MEN
➔ Condition in which a man has a low sperm count (fewer than the average 15-200 million spermcells permLof ejaculate
➔ Causes: hormonal imbalance; man’s IgA antibodies that cover the sperm; varicose vein in the scrotum
OLIGOSPERMIA
Condition in which there’s no measurable spermin aman’s ejaculate (semen)
AZOOSPERMIA
➔ ⅓ of infertile man have small deletions of the Y chromosome that remove the only copies of key genes whose products control spermatogenesis
➔ Mutations in genes that encode androgen receptors or protein fertility hormones, or that regulate sperm development or motility.
● To speed conception, amanwith lowspermcount can donate several semen samples over a period ofweeks at a fertility clinic.
● Men with spinal cord injury can use a vibrating device applied to the tip of the penis or inserted into the rectum
● Spermquality ismore important than quantity
GENETIC CAUSES
Cause: abnormalities in any part of the reproductive system
FEMALE INFERTILITY
tumor in the ovary or in the pituitary gland in the brain, underactive thyroid gland, or use of steroid-based drugs (cortisone)
Hormonal imbalance
➔ Too fewoocytes
➔ Signs: ovary with too few follicles (observed on an ultrasound scan) or elevated levels of follicle-stimulating hormone in the 3rd day of themenstrual cycle
Reduced ovarian reserve
➔ Prevent spermfromreaching an oocyte
➔ Entrap a fertilized ovum
➔ Tubal or ectopic pregnancy
➔ Can be opened by surgery
Uterine tubes blockage
➔ Fibrosis
➔ Endometriosis
Excess tissue growing in the uterine lining
➔ CERVICAL MUCUS (due to infection) can entrap sperm
➔ VAGINAL SECRETIONS - may be so acidic or alkaline
➔ Too littlemucus can prevent conception
➔ Mucus in a woman’s body sometimes has antibodies that attack sperm
Secretions in vagina & cervix
can entrap sperm
CERVICAL MUCUS (due to infection)
may be so acidic or alkaline
VAGINAL SECRETIONS
They can tell when they are most fertile by suing an OVULATION PREDICTOR TEST which detects a peak in the level of luteinizing hormone. T OR F
TRUE
Older way to detect onset evaluation is to record body temperature each morning using digital thermometer with subdivisions of hundredths of a degree Fahrenheit > indicate 0.4-0.6 rise in temperaturewhen ovulation starts. T OR F
True
Sperm can survive in a women’s body for up to ____, but the oocyte is only viable for____ after ovulation.
5 days, 24-48 hours
➔ Can stimulate ovulation, but can also causewomen to “superovulate”
FERTILITY DRUGS
commonly used drug, raises the chance ofhaving twins from1-2% to 4-6%
CLOMIPHENE
If a woman’s ovaries are completely inactive or absent (due to a birth defect or surgery)
Can become pregnant only is she uses a donor oocyte
★ SPERM COUNT
★ SPERMMOTILITY ★ SPERMMORPHOLOGY
(performed by urologists)
★ Y chromosome deletions
oligospermia - genetic counselor
★ Unidentified cause of infertility - gynecologist checks the thewoman to see that reproductive organs are present &functioning
INFERTILITY TESTS (MEN)
Detects the surge in luteinizing hormone (LH) that occurs before ovulation
OVULATION TESTING
Detects abnormalities in the uterine cavity
HYSTEROSALPINGOGRAPHY
Determines the quality and quantity of eggs available for ovulation
OVARIAN RESERVE TESTING
IMAGING TESTS
uterine/fallopian tube disease
PELVIC
ULTRASOUND
IMAGING TESTS
used to see details inside the uterus that can’t be seen on a regular ultrasound
SONOHYSTEROGRAM (saline infusion sonogram)
IMAGING TESTS
Involves collecting cells fromyour cervix
PAP SMEAR
IMAGING TESTS
Check levels of ovulatory hormones as well as thyroid and pituitary hormones
OTHER HORMONE TESTING
IMAGING TESTS
May identify endometriosis, scarring, blockages or irregularities of the fallopian tubes, and problems with the ovaries and uterus
LAPAROSCOPY
Helps determine whether there’s a genetic defect causing infertility
GENETIC TESTING
Procedures that replace a gamete or provide a uterus to help peoplewith fertility problems have children
➔ Can be performed onmaterial from: ★ The parents-to-be (“nondonor”)
★ Donors
★ May be”fresh” (collected just prior to the procedure)
★ “Frozen” (preserved in liquidnitrogen)
➔ Man can be a genetic parent
★ Contributing half of his genetic self in his sperm
➔ Woman can be both
★ Genetic parent - donating oocyte ★ Gestational parent - loaning her uterus
ASSISTED REPRODUCTIVE TECHNOLOGIES (ARTs)
➔ Oldest ART (artificial insemination), a doctor places a donated sperm into a woman’s cervix or uterus
➔ A woman might seek IUI using donor sperm:
➢ Her partner is infertile or has a mutation that the couple wishes to avoid passing to their child
➢ To be a single parent without having sex
➢ Lesbian couple to have a child
Intrauterine Insemination (IUI)
➔ Surrogate mother agrees to bear a child for another womanwho is incapable to conceive herself by being inseminatedwith theman’s sperm
➔ Both genetic&gestationalmother ➔ Surrogate mother lends only her uterus, receiving a fertilized ovum conceived from a man & a woman who has healthy ovaries, but lack a functional uterus
➔ “Embryo transfer to a host uterus” ➔ “Gestational-nly surrogatemother
Surrogate Motherhood
➔ “Fertilization in glass”, sperm&oocytes join in a laboratory dish
➔ A woman might undergo IVF if her ovaries & uterus work but her uterine tubes are blocked
➔ Chances of a live birth following IVF: 20-35%per cycle
➔ Factors that lower the likelihood of success: ★ Maternal age ★ Increased time being fertile ★ Number of previous and failed IVF attempts
★ Use of a woman’s own oocytes rather than a donor’s
★ Infertilitywith a known cause
➔ Embryos resulting from IVF that are not soon implanted in the woman can be frozen in liquid nitrogen (“cryopreserved” or vitrified”) for later use ➢ Cryoprotectant chemicals are used to prevent slats frombuilding up or ice crystals fromdamaging delicate cell parts
➢ Freezing takes free hours; thawing about halfanhour
In Vitro Fertilization (IVF)
➔ An infertility treatment that injects a sperm cell nucleus into an oocyte
➔ Helpful formenwho have lowspermcounts ormany abnormal sperm
➔ Makes fatherhood possible for men who cannot ejaculate
Intracytoplasmic sperm injection (ICSI)
➔ Oocytes can be stored (freezing) ➔ Reasons to freeze oocytes: ★ Cancer
treatment (radiation
therapy or chemotherapy) that can harm oocytes & cause early menopause
★ Exposure to toxins or teratogens in theworkplace
★ Disease of the ovaries ★ Premature ovarian failure, which may be due to XO syndrome or fragile X syndrome
★ Ovary removal to prevent ovarian cancer due to a BRCA1 or BRCA2 mutation
★ Inability to obtain viable sperm on the day of IVF
★ Extra oocytes remain after IVF ★ Donation ★ Delaying motherhood for personal reasons
➔ Oocytes are frozen in liquid nitrogen at temperatures below -40C, when they are at metaphase of the secondmeiotic division
➔ Problems: ★ If the spindle comes apart as the cell freezes, the oocyte may lose a chromosome, which would devastate development
★ Retention of a polar body, leading to a diploid oocyte
➔ To minimize risk of damage to oocytes when freezing ➢ They are first treated with crypto protectants that remove water & prevent ice crystal formation
➔ When the frozen oocytes are to be used ➢ They are slowly warmed & rehydrated by gradually removing the crypto protectants
➔ Frozen oocytes are fertilized in vitro using ICSI because the outermost layer (zona
Oocyte Banking (Freezing) and Donation
➢ Freezing strips of ovarian tissue that can be stored, thawed, & reimplanted at various sites
➢ The tissue ovulates & the oocytes are collected & fertilized in vitro.
Ovarian
tissue
cryopreservation
➢ Chosenmethod bywomen who have no oocytes or wish to avoid passing on a mutation
➢ Oocyte donors are
typically younger women & some women become donors when
they
undergo IVF & have “extras”
Oocyte donation
➔ Often teamed with IVF to detect genetic & chromosomal
abnormalities pregnancy starts
➔ Diagnosis: if it detects a specific gene variant known to be in 1 or both parents-to-be
➔ Screening: it is is used to construct a karyotype, without looking for a specific chromosomal anomaly
➔ “Preimplantation” refers to the fact that the embryo is testes at a stage prior to when it wouldnaturally implant in the uterus
➔ Errors happen when a somatic mutations affects the sampled cells but not the rest of the embryo
Preimplantation Genetic Diagnosis
➔ ARTs introduce ownership and parentage issues ➔ Another issue: ★ Human genome information is revealing more traits to track & perhaps control in coming generations
★ ARTs operate on molecules & cells, but affect individuals &families
ARTs DISASTERS
