ABB Embryology flashcards
ABB Embryology · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Primordial germ cell origin
- Primordial germ cells arise in the yolk sac wall during early gestation and migrate to the gonadal ridge, where they colonize the developing gonads.
- Oocyte meiotic arrest
- The oocyte arrests in prophase I before birth and resumes meiosis at the LH surge, arresting again at metaphase II until fertilization.
- Sertoli vs Leydig cells
- Sertoli cells support spermatogenesis and secrete inhibin; Leydig cells respond to LH by producing testosterone.
- Acrosome function
- The acrosome is a Golgi-derived vesicle over the sperm nucleus containing enzymes such as hyaluronidase and acrosin that aid zona penetration.
- Site of fertilization
- Fertilization normally occurs in the ampulla of the fallopian tube, where sperm meets the ovulated oocyte.
- Cortical reaction
- Cortical granule release after sperm fusion modifies the zona pellucida, establishing the block to polyspermy.
- Two pronuclei (2PN)
- Two pronuclei visible 16-20 hours after insemination indicate normal fertilization with one maternal and one paternal genome.
- Compaction
- Compaction begins at the morula stage, forming tight junctions and establishing the outer cell population that becomes trophectoderm.
- Blastocyst formation
- Cavitation creates the blastocoel, and by day 5 the inner cell mass and trophectoderm are distinguishable.
- Zona hatching
- Around day 6-7 the blastocyst breaches the zona pellucida, a prerequisite for implantation into the endometrium.
- WHO semen reference limits
- WHO reference values include volume 1.4 mL or more, concentration 16 million/mL or more, total motility 42% or more, and normal morphology 4% or more.
- Density gradient preparation
- Density gradient centrifugation separates motile, morphologically normal sperm from seminal plasma, debris, and non-motile cells.
- Oocyte maturity assessment
- After denuding, a germinal vesicle or metaphase I oocyte is immature; an oocyte with an extruded polar body is metaphase II and mature.
- Trophectoderm biopsy
- Blastocyst biopsy removes 5-10 trophectoderm cells on day 5-6 for preimplantation genetic testing while preserving the inner cell mass.
- Vitrification principle
- Vitrification uses high cryoprotectant concentrations and ultra-rapid cooling to achieve glass transition and avoid ice crystal formation.
- Incubator gas conditions
- Standard embryo culture uses 37°C, 5-6% CO2 for bicarbonate buffering, and often 5% O2 in tri-gas reduced-oxygen systems.
- Bicarbonate buffering
- Culture media rely on bicarbonate buffering requiring CO2 to maintain pH near 7.2-7.4; HEPES buffers are used outside the incubator.
- Sequential media
- Sequential culture media change composition, such as pyruvate/lactate for cleavage stages and glucose for blastocyst stages, matching embryo metabolism.
- Oil overlay purpose
- An oil overlay limits evaporation, stabilizes pH and temperature, and reduces exposure to volatile contaminants in the culture dish.
- ICSI procedure
- ICSI injects a single immobilized sperm directly into the ooplasm of a metaphase II oocyte using micromanipulators and an inverted microscope.
- Assisted hatching
- Assisted hatching breaches or thins the zona pellucida mechanically, chemically, or with a laser to facilitate blastocyst hatching.
- Laser zona drilling
- A controlled laser thins or breaches the zona pellucida; energy and pulse settings must be limited to avoid embryo damage.
- Sperm immobilization
- Before ICSI, the sperm tail is crushed with the injection pipette to disrupt the membrane and ensure DNA delivery.
- Slow-freezing method
- Slow-freezing uses controlled-rate cooling with permeating cryoprotectants and seeding to induce extracellular ice formation while avoiding intracellular ice.
- Cryoprotectant types
- Permeating cryoprotectants such as DMSO and ethylene glycol enter cells; non-permeating agents such as sucrose draw water out osmotically.
- Rapid warming rationale
- Thawing must be rapid to prevent recrystallization of intracellular ice, followed by stepwise cryoprotectant removal to avoid osmotic shock.
- Blastocyst grading
- Blastocyst grading combines a numeric expansion score (1-6) with letter grades for inner cell mass and trophectoderm quality.
- Cleavage-stage grading
- Day 3 grading assesses cell number, symmetry, and fragmentation; top-quality embryos have 6-8 cells and less than 10% fragmentation.
- Time-lapse monitoring
- Time-lapse imaging allows continuous morphokinetic assessment of embryos without removing them from controlled culture conditions.
- QC versus QA
- Quality control monitors individual tests and materials, while quality assurance is the broader program ensuring consistent laboratory quality.
- Lot testing of media
- Media and consumables are lot-tested, for example by mouse embryo assay or sperm survival test, before clinical use.
- Informed consent
- Informed consent is required for assisted reproduction procedures and must address disposition of surplus embryos and cryopreserved gametes.