Lecture 20 Flashcards

1
Q

List the reasons that infertility is a growing problem in the US.

A
  • Reduced morbidity
  • Societal changes (delayed childbearing, marriage and first pregnancy)
  • More therapies available
  • Reduced expense and less taboo
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2
Q

List the forms of Assisted Reproductive Technologies (ART) in women.

A
  • Sperm donation
  • Egg donation
  • Embryo donation/adoption
  • In vitro fertilization (IVF)
  • Intrauterine insemination (IUI)
  • Traditional surrogacy
  • Gestational surrogacy
  • Sperm cryopreservation
  • Egg cryopreservation
  • Embryo cryopreservation
  • Post-mortem gamete harvesting
  • Post-death conception
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3
Q

List the stages and times of a typical IVF cycle.

A
  • TVOR, Sperm Prep and Insemination (Day 0)
  • Fertilization check (Day 1)
  • Embryo transfer (Day 3-5)
  • Embryo freeze (Day 5-6)
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4
Q

In IVF, when does the embryo culture occur?

A

Days 1 through 6

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5
Q

What does TVOR stand for?

A

Transvaginal oocyte retrieval

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6
Q

In IVF, what hormones are injected and when?

A

-FSH (-14 to -10 days till day 0) to produce eggs
- hCG (day 0) triggers egg maturation and ovulation
- Leuprolide acetate (day 0), a GnRH agonist that can control the stimulation process or be used as a trigger shot
- Progesterone supports endometrial development and early pregnancy
- Estrogen stimulates egg growth and thickens uterine lining
- Corticosteroids improves outcome of IVF with conventional insemination when sperm has autoantibodies

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7
Q

What stage of the menstrual cycle is progesterone associated with?

A

Luteal phase

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8
Q

What occurs during the luteal phase in terms of follicular development and in the endometrial cycle?

A

Corpus luteum forms and the uterine wall thickens

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9
Q

What hormones spike to trigger ovulation?

A
  • LH
  • Estrogen
  • FSH
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10
Q

What is the process of IVF egg maturation?

A
  • Ovarian stimulation/ovulation induction: adminster FSH, LH, and GnRH for 8-14 days
  • Development of eggs is monitered using trans-vaginal ultrasound
  • Blood is drawn frequently to assess ovarian estrogen production
  • When eggs are mature hCG injection initiates ovulation process
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11
Q

What is the process of IVF egg retrieval?

A
  • 34-36 hours after hCG injection, a mld sedative and painkiller is given to the patient.
  • An ultrasound probe is inserted into the vagina to visualize the ovaries and follicles
  • Needle is inserted through wall of vagina to ovaries to extract the eggs
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12
Q

What is the process of IVF fertilization?

A
  • If sperm are healthy, placed in a dish with the egg in an incubator over use
  • If they can’t fertilize the egg, a single sperm is injected into an egg using a neeedle in a process called Intracytoplasmic Sperm Injection (ICSI)
  • About 60% of IVF is performed with ICSI
  • Couples should consider genetic testing if sperm cannot fertilize the egg on their own
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13
Q

What is the process of IVF embryo transfer?

A
  • Embryos that develop from IVF are placed into the uterus 1-6 days after retrieval
  • Procedure is normally painless but patient many experience cramping
  • A long thin tube is inserted through the vagina and into the uterus to inject the embryo
  • Embryo should implant into the lining 6-10 days after retrieval
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14
Q

Third Party Assisted ARTs

A
  • Sperm Donation
  • Egg Donation
  • Surrogates and gestational carriers
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15
Q

When is egg donation a good option for women?

A
  • Have primary ovary insufficiency (POI)
  • Have had chemotherapy or radiation therapy
  • Have had surgical removal of the ovaries
  • Were born without ovaries
  • Carriers of known genetic diseases
  • Are infertile because of poor egg quality
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16
Q

What is a surrogate carrier?

A

A woman inseminated with sperm from the male partner of the couple

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17
Q

What is a gestational carrier?

A

A woman implanted with an embryo that is not biologically related to her.

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18
Q

What are the risks of traditional vs gestational surrogacy?

A

Surrogate: poses legal issues due to being genetically related to surrogate, surrogate undergoes IUI, comes with risks during development
Gestational: Costs more money, IVF is required

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19
Q

What is GIFT?

A

Laparoscopically placing mature eggs into the healthy fallopian tube along with washed sperm (Gamete intrafallopian transfer)

20
Q

What is ZIFT?

A

Zygotes are placed directely into the fallopian tubes via lapaosocpy or trasncervical falloopian tube caterization (Zygote intrafallopian transfer)

21
Q

How can a scientist tell if fertilization was a success?

A

Presence of a second polar body (meaning meiosis II occured) and male and female pronuclei both present

22
Q

What is PGS?

A

Preimplantation genetic screening screens embryos to ensure 23 pairs of chromosomes

23
Q

What is PGD?

A

Preimplatation genetic diagnosis diagnoses embryos for known genetic disorders that both the patient and partners are carriers of

24
Q

What is CCS?

A

Comprehensive chromosomal screening is a next generation sequencing that detects aneuploidy with a more in-depth scan of the genoe to find abnormalities

25
Q

Who should use biopsy/genetic screening?

A
  • Women over 35 years
  • Women who have had repeated miscarriages
  • Couples with multiple failed IVF cycles
  • Previous pregnancy with chromosomal abnormality
26
Q

What is a mosaic embryo?

A

When two or more cell populations with different genotypes are present within the same embryo

27
Q

Which mosaicism types are potentially diagnosable?

A
  • Total mosaic
  • TE mosaic
28
Q

Which mosaicism types are never diagnosable?

A
  • ICM mosaic
  • ICM/TE mosaic type I
  • ICM/TE mosaic type II
29
Q

Consequences for embryo survival in terms of mosaic embryos are unknown

30
Q

What are the features of slow-rate cryopreservation?

A
  • Low concentration of cryoprotectant
  • Programmable freezer
  • Slow cooling rate
  • Closed devices
  • Inexpensive devices
31
Q

What are the features of vitrification cryopreservation?

A
  • High concentration of cryoprotectant
  • No mechanical equipment
  • Rapid cooling
  • Open or closed devices
  • Expensive devices
32
Q

When is totipotency lost?

A

When blastomeres reach the 8 cell stage after which differentiation starts

33
Q

Are embryonic stem cells completely totipotent?

A

No, as they are not interchangeable as differentiation starts.

34
Q

How do embryonic stem cells (ES) differ from all other cells?

A
  • They can be induced to change or differentiate into virtually any cell before differentiation starts
  • Somatic cells which have finite lifespans, ES cells can grow indefinitely in culture
35
Q

What are factors of somatic cells compared to induced pluripotent stem cells?

A
  • Limited proliferation
  • Pluripotency genes methylated
  • Tissue-specific cell morphology
  • X-chromosome inactivated
  • Active G1 celll cycle checkpoint
  • Expression of somatic cell specific markers
36
Q

What are factors of induced pluripotent stem cells compared to somatic cells?

A
  • Self-renewal
  • Pluripotency
  • ES cell morphology
  • Demethylation of pluripotency genes
  • Reactivation of pluripotency genes
  • X-chromosome reactivation (female cells)
  • Telomerase activity
  • Loss of G1 checkpoint
37
Q

What reprogramming factors can turn somatic cells into induced pluripotent stem cells?

A
  • Sox2, Oct4, Klf4, c-Myc
  • Sox2, Oct4, Nanog, Lin28
  • Sox2, Oct4, Klf4
  • Etc.
38
Q

How does differentiation capability change throughout development?

A
  • Pre-blastocyst: totipotent
  • Blastocyst: pluripotent
  • Fetus: multipotent
  • Adult: unipotent
39
Q

How exactly did ovarian function regenerate using placental-derived (PD) mesenchymal stem cells?

A
  • PD-MSC transplatation increased estradiol level in ovarietomized (Ovx) rats compared with the non-transplantation group (NTx)
  • Spheroid PD-MSCs exhibited a significantly higher efficiency of engraftment onto ovarian tissues at 2 weeks.
  • Nanos3, Nobox and LHx8 were also significantly increased in Spheroid group
  • PD-MSC transplantation restored ovarian function in Ovx rats by increasing esttrogen production & enhancing folliculogenesis-related gene expression levels
  • Spheroid-cultured PD-MSCs have enhanced therapeutic potential via increased engraftment efficiency.
40
Q

How can oocytes be developed from stem cells?

A
  • ES cells and induced pluripotent stem cells have been differentiated into oocytes that have grown to full follicular maturity in mice
  • In humans, follicle maturation through oocyte IVM to produce heathy offspring has been achieved
  • No offspring production as of yet
  • Further research needs to be done which is difficult as ethics still needs to be considered.
41
Q

What is a Free Martin?

A

Sterile heifer sharing placenta with twin bull fetus.

42
Q

How was Dolly the sheep cloned?

A

Nucleus from a ewe’s somatic cell was taken and implanted in an enucleated egg cell from another ewe, which was then fused with electrical pulses to induce fertilization.

43
Q

Four methods to alter gene expression in livestock in vivo

A
  • RNA interference (RNAi)
  • Zinc-finger nucleases (ZFN)
  • Transcription activatory-like effector nucleases (TALENS)
  • Clustered regularly interspersed palindromic repeats (CRISPR) and CRISPR associated protein 9 (Cas 9)
44
Q

Advantages and disadvantages for RNAi

A
  • Advantages: diminishes gene expression
  • Disadvantages: diminishes genes expression and variability between animals over time
45
Q

Advantages and disadvantages for CRISPR-Cas 9

A
  • Advantages: Ablates gene expression
  • Disadvantages: May be lethal