Which germ layer gives rise to the olfactory epithelium?
Ectoderm (surface ectoderm)
Which 2 structures in the female embryo are formed from the genital tubercle under the effects of estrogen?
Glans clitoris, vestibular bulbs
Which embryologic structure becomes the lower part of the vagina?
Urogenital sinus
What are the major zygotic stages before formation of the embryonic disc?
Fertilized egg, 2-cell stage, morula, blastocyst, formed embryonic disc
Which germ layer gives rise to the aorticopulmonary septum?
Ectoderm (neural crest)
Which 2 structures in the male embryo are differentiated under the effects of dihydrotestosterone from the urogenital sinus?
Prostate and bulbourethral glands (of Cowper)
Why does holoprosencephaly develop with a field defect type error of organ morphogenesis?
Due to tissue disturbances during development in a contiguous physical space
How many eggs and sperm do monozygotic twins arise from?
Monozygotic twins arise from 1 fertilized egg (1 egg + 1 sperm) that splits in early pregnancy
What is the basis of developmental abnormality in hypospadias?
Abnormal opening of the penile urethra on the ventral penis secondary to failure of the urethral folds to fuse
What is the likely effect on development when a 2-week-old embryo is exposed to an unknown teratogen?
Either embryonal demise or no abnormalities (all-or-none effect before week 3)
When does the embryo′s heart begin to beat?
Four weeks
What diffuses from the fetal circulation into the maternal circulation via the placenta?
Carbon dioxide, water, hormones, urea, waste products
Which layer of the placenta synthesizes hormones, such as human chorionic gonadotropin (hCG)?
Syncytiotrophoblast
Which structure do astrocytes, central nervous system neurons, ependymal cells, neurohypophysis, oligodendrocytes, and pineal gland derive from?
Neural tube
Which type of morphogenesis error results in the lack of an organ because of absence of primordial tissue?
Agenesis
Which day of embryogenesis does a zygote divide into a morula?
Day 4
What maternal condition during pregnancy can lead to cardiac defects, caudal regression syndrome, neural tube defects, neonatal hypoglycemia and respiratory distress syndrome?
Diabetes
What is the function of 5α-reductase?
Converts testosterone to dihydrotestosterone (DHT)
Which 2 germ layers give rise to the skin layers?
Ectoderm (surface ectoderm): epidermis; mesoderm: dermis
Hypospadias is associated with which 3 conditions?
Inguinal hernia, chordee, cryptorchidism
Which vascular structures carry oxygen-rich blood from the mother to the fetus in the umbilical cord?
Umbilical vein
Which germ layer gives rise to the spinal cord?
Ectoderm (neural tube)
Which germ layer gives rise to the testes and ovaries?
Mesoderm
During what weeks of embryonic development does organogenesis occur?
Weeks 3–8 (the embryonic period)
Which teratogen may cause phocomelia due to in utero exposure?
Thalidomide
Which medication used during pregnancy may cause aplasia cutis congenita in a newborn?
Methimazole
What are 2 complications associated with Müllerian duct anomalies?
↓ fertility, ↑ risk of complicated pregnancy
Which effect can maternal consumption of fish with high levels of methylmercury have on a fetus?
Neurotoxicity
Why is there a decreased chance of attack by the maternal immune system on the placenta?
Lack of MHC I expression in the syncytiotrophoblast
Which 2 ligaments are formed from the gubernaculum in females?
Ovarian ligament, round ligament of the uterus
Which embryonic process is occurring when the fetus is most susceptible to teratogens?
Organogenesis
Which cells could lead to improper development of male internal genitalia due to impaired hormone release?
Leydig cells, which produce testosterone
How old is the embryo when it exists as a trilaminar disc?
Three weeks = 3 layers
Which type of twin pregnancy will result if a morula is split just before becoming a blastocyst?
Monozygotic (monochorionic, diamniotic)
Which cell is released from a follicle after ovulation?
Secondary oocyte
Which organ in the fetus can be damaged with the use of an angiotensin-converting enzyme (ACE) inhibitor?
Kidney
Which anticoagulant is safe for use during pregnancy?
Heparin
Which 3 effects are likely to result from a patient′s use of cocaine during pregnancy?
Preterm delivery, low birth weight, and fetal growth restriction
Which type of twin pregnancy results from the splitting of a blastocyst just before embryonic disc formation?
Monozygotic (identical), monochorionic, monoamniotic twins
Which type of birth defect is associated with the use of folate antagonists during pregnancy?
Neural tube defects
Which week of development can the first male/female sex characteristics be distinguished in a fetus?
Week 8
How do nicotine and carbon monoxide exposure in utero increase the risk for low birth weight?
Due to vasoconstriction caused by nicotine, and impaired oxygen delivery due to carbon monoxide
Which hormone stimulates the corpus luteum to secrete progesterone during the 1st trimester of pregnancy?
Human chorionic gonadotropin (hCG)
Which abnormality, detected on physical examination, may be due to persistent patent processus vaginalis in a male?
Hydrocele
How old is the embryo when the initial development of the notochord and primitive streak are noted?
Three weeks
Which embryonic structure is the fetal neural plate derived from?
Ectoderm overlying the notochord
In the maternal circulation, which vessels carry oxygen-rich blood to the lacunae?
Endometrial arteries
Which germ layer gives rise to the kidneys and adrenal cortex?
Mesoderm
Which germ layer gives rise to the epithelial lining of the oral cavity?
Ectoderm (surface ectoderm)
What is the postnatal derivative of the notochord?
Nucleus pulposus of intervertebral discs
