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62 Cards in this Set
- Front
- Back
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What happens during the 2nd week?
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2 germ layers (bilaminar disk): epiblast (becomes primitive streak to give rise to intraembryonic mesoderm and part of the endoderm) and hypoblast.
2 cavities: amniotic cavity, yolk sac 2 components to placenta: cytotrophoblast, syncytiotrophoblast |
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What happens during the 3rd week?
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3 germ layers (gastrula): ectoderm, mesoderm, endoderm
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What happens during the 4th week?
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4 heart chambers
4 limb buds (SHH) |
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What structures are derived from neural crest?
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ANS, DRG, CNs, celiac ganglion, melanocytes, chromaffin cells of adrenal glands, parafollicular C cells of thyroid, Schwann cells, pia and arachnoid matter, bones of skull, odontoblasts, aorticopulmonary septum (SPRIAL SEPTUM)
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What structures are derived from the endoderm?
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Gut tube epithelium and derivatives (lung, liver, pancreas, thymus, PARATHYROID, THYROID FOLLICULAR CELLS)
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What structures are derived from the mesoderm?
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Muscle, bone, connective tissue, serous linings of body cavities (pertoneum), SPLEEN, CV structures, lymphatics, blood, bladder, urethra, vagina, eustachian tube, kidneys, adrenal cortex, skin dermis, testes, ovaries
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What are the mesodermal defects?
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VACTERL: Vertebral, anal atresia, cardiac, T-E fistulas, renal, limb defects
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When do the chorion and amnion form?
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Chorion at 3 days, amnion at 8 days. Twins that form after the amnion forms are at risk of being conjoined.
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What hormone is bCH similar to?
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LH- stimulates progesterone secretion from the corpus luteum during the first trimester.
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What is the allantois?
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It derives from the yolk sac during the 3rd week and becomes the urachus, a duct between the bladder and yolk sac. It also gives rise to the umbilical vessels.
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What happens if the urachus fails to obliterate?
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Patent urachus- Urine discharge from the umbilicus.
Vesicourachal diverticulum- Outpouching of the bladder Urachal sinus- purulent discharge from the umbilicus Urachal cyst- Found between the 2 ends of the urachus |
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What is the vitelline duct and what happens to it?
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It is also called the omphalomesenteric duct and connects the yolk sac to the midgut lumen. It obliterates by the 7th week.
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What happens if the vitelline duct does not close?
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Vitelline fistula- Meconium discharge from the umbilicus
Merckel's diverticulum- Partial closure leads to a patent portion attached to the ileum (a band may connect it to the umbilicus). There is ectopic gastric or pancreatic mucosa (melena, periumbilical pain). It can lead to intestinal obstruction, volvulus, and intusussception. Diagnose with 99mmTc-pertechnetate. |
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What does the truncus arteriosus give rise to?
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Ascending aorta and pulmonary trunk
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What does the bulbus cordis give rise to?
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Smooth parts of RV and LV
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What does the primitive ventricle give rise to?
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Trabeculated parts of RV and LV
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What does the left horn of the sinus venosus give rise to?
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Coronary sinus
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What does the right horn of the SV give rise to?
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Smooth part of the RA
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What do the right common cardinal vein and right anterior cardinal vein give rise to?
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SVC
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What do the primitive atria give rise to?
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Trabeculated RA and LA
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What pathological conditions arise from the truncus arteriosus?
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TGV (failure to spiral), TOF (skewed AP septum development), persistent TA (partial AP septum development)
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Where does fetal erythropoeisis take place?
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Yolk sac (3-8 weeks)
Liver (6-30 weeks) Spleen (9-28 weeks) Bone marrow (29 weeks onward) |
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What does the Telencephalon (from proencephalon) give rise to?
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Cerebral hemispheres (walls)
Lateral ventricles (cavities) |
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What does the Diencephalon (from proencephalon) give rise to?
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Thalami, hypothalamus, optic tracts (walls)
3rd ventricle (cavities) |
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What does the Mesencephalon give rise to?
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Midbrain (walls)
Aqueduct (cavities) |
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What does the Metencephalon (from rhombencephalon) give rise to?
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Cerebellum, pons (walls)
4th ventricle (cavities) |
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What does the Myelencephalon give rise to (from rhombencephalon)?
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Medulla (walls)
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What is syringomyelia?
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Enlargement of the central canal of the spinal cord at the anterior commissure. Crossing fibers of the spinothalamic tract are damaged first to cause a cape like bilateral loss of pain and temperature sensation in the UE. Atrophy of the intrinsic muscles of the hands (often confused with ALS).
Usually occurs C8-T1 and associated with Chiari II malformation (cerebellar tonsillar herniation through the foramen magnum) |
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What is a cleft lip?
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Failure of fusion of the maxillary and medial nasal processes
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What is a cleft palate?
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Failure of fusion of the lateral palatine processes, the nasal septum, and/or the median palatine process.
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What abnormality arises from failure of rostral abdominal wall closure?
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Sternal defects
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What abnormality arises from failure of caudal abdominal wall closure?
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Bladder exstrophy
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What causes duodenal atresia and what disorder is it associated with?
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Failure of the midgut to recanalize. Associated with Trisomy 21.
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What causes jejunal, ileal, and colonic atresia?
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Vascular accident (apple peel atresia).
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What abnormality arises from failure of lateral abdominal wall closure?
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Omphalocele- persistence of herniation of abdominal contents into umbilical cord covered by periotoneum (normal in the 6th week to allow rapid growth of the intestine and liver despite slower growth of the abdominal cavity; should return by week 10). Midline
Gastroschisis- Extrusion of abdominal contents through abdominal folds; not covered by periotoneum. Not midline Both have elevated AFP |
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What causes an annular pancreas?
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Ventral bud abnormally encircles the 2nd part of the duodenum and forms a ring of pancreatic tissue that may cause duodenal narrowing and stenosis. It is associated with polyhydramnios, Downs, duodenal and esophageal atresia, imperforate anus, and Meckle's diverticulum.
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What causes a pancreatic divisum?
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Ventral and dorsal buds fail to fuse at 8 weeks (asymptomatic)
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What does the ureteric bud give rise to?
What does the metanephric mesenchyme give rise to? |
Ureteric bud (derived from the caudal end of the mesonephros)- Ureter, pelvises, through collecting ducts. Canalized by week 10.
Metanephric mesenchyme (induced to differentiate by the ureteric bud)- Glomerulus and renal tubules to distal convoluted tubules |
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How does a horseshoe kidney form?
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Inferior poles of the kidneys fuse and as they ascend, they get trapped under the IMA and remain low. Normal function. See this in Turner's
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What does the genital tubercle give rise to?
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Male- glans penis, corpus cavernosum/spongiosum
Female- glans clitoris, vestibular bulbs |
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What does the urogenital sinus give rise to?
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Male- Bulbourethral glands, Prostate gland
Female- Greater vestibular blands (Bartholin), urethral and paraurethral glands (Skene) |
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What do the urogenital folds give rise to?
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Male- Ventral shaft of the penis (urethra- incomplete fusion gives hypospadias)
Female- Labia minora |
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What does the labioscrotal swelling give rise to?
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Male- scrotum (malunion causes bifid scrotum)
Female- Labia majora |
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What gives rise to epispadias and what is it associated with?
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Abnormal positioning of the genital tubercle; associated with extrophy of the bladder
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What causes hydrocele?
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Incomplete obliteration of the processus vaginalis; associated with indirect abdominal hernia.
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What gene is important in patterning along the AP axis?
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SHH- mediates ectodermal derivatives; defect results in holoproencephaly
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What gene is involved in organizing the dorsal-ventral axis?
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Wnt-7 (made at AER)
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What gene is important in lengthening the limbs?
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FGF- mutated in achondroplasia; produced at AER and stimulates mitosis of the underlying mesoderm
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What gene is involved in segmental organization of the embryo in a craniocaudal direction?
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Homeobox- codes for TFs
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What is the difference between a malformation and a deformation?
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Malformation is intrinsic and occurs in the embryonic period (weeks 3-8)
Deformation is extrinsic and occurs after the embryonic period |
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What abnormalities are associated with FAS?
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MR, microcephaly, holoproencephaly, facial abnormalities, limb dislocation, heart and lung fistulas
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What disorders is holoproencephaly associated with?
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Patau's syndrome
FAS Cleft lip/palate SHH GENE |
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What disorders are associated with polyhydramnios?
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Anencephaly, duodenal atresia, TE fistula
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What is Dandy-Walker?
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Large posterior fossa with absent cerebellar vermis and cystic enlargement of the 4th ventricle. Spina bifida and hydrocephalus may result.
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What is Chiari II?
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Cerebellar tonsilar herniation through the foramen magnum with aqueductal stenosis and hydrocephaly. Associated with syringomyelia and thoracolumbar myelomeningocele.
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What is the normal remnant of the thyroglossal duct?
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Foramen cecum
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What causes a branchial cleft cyst?
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Persistent cervical sinus (should be obliterated by the proliferation of 2nd arch mesenchyme)
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What causes a fixed cecum in the RUQ?
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Malrotation of the gut around the SMA
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How does a TE fistula present?
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Cyanosis, choking, immediate vomiting with first feeding, excessive salivation, air bubble on stomach CXR, failure to pass NG tube into stomach
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How does pyloric stenosis present?
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Palpable olive in epigastric area, nonbilous PROJECTILE vomiting at 2 weeks of age, hypochloremic/hypokalemic metabolic alkalosis
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What is the most common site of obstruction in the GU system?
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Uteropelvic junction with kidney- last to canalize
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What is associated with oligohydramnios?
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Potters syndrome, placental insufficiency, bilateral renal agenesis, posterior urethral valves in males (cannot excrete urine)
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