Flashcards in One Word_Embryology Deck (51):
Produced at apical ectodermal ridge (thickened ectoderm at distal end of each developinf limb). Necessary for proper organization along dorsal-ventral axis.
Treacher Collins syndrome
1st-arch neural crest fails to migrate → mandibular hypoplasia, facial abnormalities
Teratogens: X-rays, anticonvulsants
Bone deformaties, fetal hemorrhage, abortion
Teratogens: Vitamin A (excess)
Extremely high risk for spontaneous abortions and birth defects (cleft palate, cardiac abnormalities)
Inhibition of intestinal folate absorption → Neural tube defects
Limb defects ("flipper" limbs)
Teratogens: Smoking (nicotine, CO)
Preterm labor, placental problems, IUGR, ADHD
Teratogens: Maternal diabetes
Caudal regression syndrome (anal atresia to sirenomelia)
Ebstein's anomaly (atrialized right ventricle)
Teratogens: Iodide (lack or excess)
Congenital goiter or hypothyroidism
Teratogens: Folate antagonists
Neurol tube defects
Teratogens: Diethylstilbestrol (DES)
Vaginal clear cell adenocarcinoma
Abnormal fetal development and fetal addiction; placental abruption
CN VIII toxicity
Teratogens: Alkylating agents
Absence of digits, multiple anomalies
Leading cause of birth defects and mental retardation; fetal alcohol syndrome
Teratogens: ACE inhibitors
Sonic hedgehog gene
Produced at base of limbs in zone of polarizing activity. Involved in patterning along anterior-posterior axis.
Involved in segmental organization or embryo in a craniocaudal direction
Produced at apical ectodermal ridge. Stimulates mitosis of underlying mesoderm, providing for lengthening of limbs.
Embryology: What is associated with Epispadias?
Exstrophy of the bladder
Embryology: Vitelline duct
7th week, obliteration of vitelline duct (omphalomesenteric duct), which connects yolk sac to midgut lumen.
Embryology: Uteropelvic junction with kidneys
last to canalize → most common site of obstruction (hydronephrosis) in fetus
Embryology: Urachal duct
3rd week, yolk sac forms allantois, later becomes urachus, a duct between bladder and yolk sac.
Embryology: Truncus arteriosus pathology
Failure neural crest migration: ①Transposition of great vessels (failure to spiral); ②Tetralogy of Fallot (skewed AP septum development); ③Persistent TA (partial AP septum development)
Embryology: Truncus arteriosus
Ascending aorta and pulmonary trunk
outer layer of chorionic villi; secretes hCG (structurally similar to LH; stimulates corpus luteum to secrete progesterone during first trimester)
Embryology: Patent foramen ovale
Abnormal interatrial septum development caused by excessive resorption of septum primum and/or secundum
persistence of herniation of abdominal contents into umbilical cord, covered by peritoneum
Embryology: Jejunal, ileal, colonic atresia
Due to vascular accident (apple peel atresia)
abnormal opening of the penile urethra on inferior (ventral) side of penis due to failure of urethral folds to close
↓seperation of hemispheres across midline; results in cyclopia; associated with Patau's syndrome, severe fetal alcohol syndrome, and cleft lip/palate.
extrusion of abdominal contents through abdominal folds; not covered by peritoneum
abnormal opening of penile urethra on superior (dorsal) side of penis due to faulty positioning of genital tubercle
Embryology: Duodenal atresia
Failure to recanalize (trisomy 21)
Embryology: Decidua basalis
Maternal component, derived from the endometrium. Maternal blood in lacunae.
Embryology: Dandy-Walker syndrome
large posterior fossa; absent cerebellar vermis with cystic enlargement of 4th ventricle. Can lead to hydrocephalus and spina bifida.
inner layer of chorionic villi. Cyto makes cells.
Only larynx muscle innervated by the superior laryngeal branch
Embryology: Bulbus cordis
Right ventricle and smooth parts (outflow tract) of left and right ventricle
Embryology: Arnold chiari II
cerebellar tonsillar herniation through foramen magnum with aqueductal stenosis and hydrocephaly. Often presents with syringomyelia, thoraco-lumbar myelomeningocele.
Malformation of anterior end of neural tube; no brain/calvarium, elevated AFP, polyhydramnios (no swallowing center in brain).
Descent of testes and ovaries: Processus vaginalis (evagination of peritoneum)
Female remnant: Obliterated Male remnant: Forms tunica vaginalis
Descent of testes and ovaries: Gubernaculum (band of fibrous tissue)
Female remnant: Ovarian ligament + round ligament of uterus Male remnant: Anchors testes within scrotum
Congenital pharyngocutaneous fistula
persistence of cleft and pouch → fistula between tonsillar area, cleft in lateral neck
Branchial cleft derivatives
1st cleft - external auditory meatus 2nd - 4th clefts - form temporary cervical sinuses, which are obliterated by proliferation of 2nd arch mesenchyme Persistent cervical sinus → branchial cleft cyst within lateral neck
Aortic arch derivatives
1st-part of Maxillary artery (branch of external carotid) 2nd-Stapedial artery and hyoid artery 3rd-common Carotid artery and proximal part of internal carotid artery 4th-on left, aortic arch; on right, proximal part of right subclavian artery 6th-proximal part of pulmonary arteries and (on left only) ductus arteriosus