Infertility/ART

Question 1

Natural fertility steps and infertility 1

Answer 1

• Fertilization of oocyte must occur within 24hrs of ovulation, sperm bind to ZP3-> acrosome reaction-> fusion of egg and equatorial region of sperm head
• Embryo development normally takes place within fallopian tube, inner cell mass of embryo contains stem cells
• If oocyte is fertilized it will reach the uterus in 5 days and will be implanted by 7 days after ovulation

Question 2

Natural fertility steps and infertility 2

Answer 2

• Infertility: inability to conceive after 12 mos of regular sexual intercourse w/o contraception
• Age determines pregnancy success
• Work up of fertilization consists of analyzing the 3 parts of fertility: eggs (ovulation and quality), sperm (concentration, motility, morphology), and mullerian structures (fallopian tubes and uterus)

Question 3

Basic principles of ART (assisted reproductive technologies)

Answer 3

• Oocytes can be retrieved from follicles after FSH/LH stimulation
• Cryopreservation allows for fertility preservation
• Donation allows for pregnancy after menopause (using someone else’s eggs)
• Sperm can be injected into oocyte (ICSI) or naturally bind to it (IVF)
• After IVF multiple embryos are placed in the uterus

Question 4

Principal factor in reproductive ageing

Answer 4

• Oocyte quality (decreases after 35): consists of cell division, DNA replication, and implantation success rates
• Older cells have decreased energy production, increased chromosomal errors and miscarriages, and decreased implantation rates
• Uterus maintains receptivity w/ age (not the limiting factor)

Question 5

Gender selection (PGD)

Answer 5

• Pre-implantation genetic Dx: analyze blastomere (single cell of an embryo) from cleaving embryo, analyze karyotype for X and Y chroms
• Then replace only embryos of desired gender/w/o diseases
• Problems w/ PGD: limited time for Dx (cryopreservation is alternative), damage to embryo (decreases implantation), mosaicism (biopsied blastomere may not represent rest of embryo)
• The blastomere differentiates into inner cell mass (will become fetus, contains stem cell) and trophectoderm (will become placenta