Aponeurosis — Embryology Question Bank OmpathStudy

A consolidated Year 1 Embryology spot-question bank for the Aponeurosis collection, drawn from eight revision papers, organised by developmental topic — gametogenesis, fertilization, fetal membranes and the placenta, embryonic folding, neural tube development, and the congenital anomalies linked to each stage. Tap any answer to reveal it. Gametogenesis & Ovarian/Uterine Cycle Q1: State the basis for A; state the basis for C Answer: Basis for A (proliferative phase): oestrogen presence Basis for C (secretory phase changes/menstruation): progesterone lack (withdrawal) --- Q2: Identify the structure shown; its basis; functions of the zona pellucida Answer: Structure shown: molar pregnancy (hydatidiform mole) Basis: an extra set of paternal chromosomes Functions of the zona pellucida: prevents polyspermy; ensures species specificity of fertilization; protects the primary oocyte --- Q3: Identify the hormones plotted X, Y, Z, W (menstrual cycle correlation) Answer: X (sharp, tallest peak exactly at day 14): luteinizing hormone (LH) — the LH surge that triggers ovulation W (smaller peak coinciding with X, at day 14): follicle-stimulating hormone (FSH) Z (moderate peak just before day 14): oestradiol — oestrogen peaks shortly before the LH surge Y (broad peak around day 21, mid-luteal phase): progesterone — secreted by the corpus luteum --- Q4: Spermatogenesis — identify A–G Answer: A: spermatocytogenesis/mitosis B: primary spermatocyte C: first meiotic division D: secondary spermatocyte E: second meiotic division F: spermatids G: spermiogenesis --- Q5: Mature Graafian follicle — identify A–G Answer: A: corona radiata B: zona pellucida C: oocyte D: follicular antrum E: granulosa cells F: theca G: cumulus oophorus --- Q6: Identify A–C Answer: Left image — A: zona pellucida Left image — B: oocyte Left image — C: polar body Right image — A: blastocoel Right image — B: trophoblast Right image — C: embryoblast --- Q7: Hormonal basis of events A and B; two phases of spermatogenesis (2+2 marks) Answer: Event A (endometrial shedding/menstruation) hormonal basis: withdrawal of oestrogen and progesterone following corpus luteum regression Event B (ovulation) hormonal basis: the mid-cycle LH surge Two phases of spermatogenesis: spermatocytogenesis (proliferation and meiotic division of spermatogonia); spermiogenesis (differentiation of spermatids into mature spermatozoa) --- Q8: Identify the types of conjoined twins displayed; two meiotic arrests during oogenesis (2+2 marks) Answer: A — craniopagus (twins conjoined at the head) B — parapagus (twins conjoined side-by-side, sharing a pelvis) Two meiotic arrests during oogenesis: arrest in prophase I (diplotene stage — persists from fetal life until puberty); arrest in metaphase II (persists until fertilization) --- Fertilization & Early Development Q9: Identify the condition Answer: Blighted ovum (anembryonic pregnancy) --- Q10: State the stage at which this congenital anomaly forms; two sources of amniotic fluid Answer: Stage at which conjoined twinning forms: the primitive streak stage Two sources of amniotic fluid: Foetal urine Secretions from amnioblast cells Also accepted: maternal tissue fluid, by diffusion --- Q11: State two fates of B; four results of longitudinal folding Answer: Two fates of B (yolk sac): Dorsal part — incorporated to form the primitive gut Ventral part — degenerates Also visible in this image (for revision): the yolk sac is also an early site of haematopoiesis Four results of longitudinal folding of the embryo: Primary curvature formation Descent of the heart Connecting stalk formation Amniotic cavity expansion Also accepted: oesophagus elongation --- Q12: Implantation — identify A–H Answer: A: trophoblastic lacunae B: syncytiotrophoblast C: cytotrophoblast D: amniotic cavity E: epiblast F: hypoblast G: exocoelomic (Heuser's) membrane H: umbilical vesicle --- Q13: Trilaminar disc (epiblast) — identify A–D Answer: A: notochord B: primitive pit C: primitive node D: primitive groove --- Q14: State the anomaly and its basis Answer: Sacrococcygeal teratoma Basis: failure of degeneration/regression of the primitive streak Typically contains tissue from all three germ layers (source key leaves the follow-up unanswered) --- Q15: One derivative and one anomaly of B; one function and one anomaly associated with D (2+2 marks) Answer: B — notochord. Derivative: nucleus pulposus of the intervertebral disc. Anomaly: chordoma (tumour of notochordal remnants) D — primitive gut tube. Function: gives rise to the epithelial lining and glands of the gastrointestinal tract and its associated organs (liver, pancreas). Anomaly: duodenal atresia --- Q16: State the anomaly depicted and give its basis Answer: Molar pregnancy / hydatidiform mole Basis: the paternal set of chromosomes outnumbers/predominates over the maternal set Complete mole: entirely paternal (androgenetic), diploid Partial mole: triploid, from dispermy --- Q17: State the anomaly depicted and give its basis A