Term
| what is the role of the sonic the hedgehog gene? |
|
Definition
| patterning along the *AP axis. produced at the base of the limbs in the *zone of polarizing activity. |
|
|
Term
| what is the role of the Wnt-7 gene? |
|
Definition
| this is produced at the *apical ectodermal ridge and is necessary for proper organization along the *dorsal-ventral axis. |
|
|
Term
| what is the role of the FGF gene? |
|
Definition
| stimulation of *mitosis in the underlying mesoderm - provides for lengthening of limbs. produced at the *apical ectodermal ridge. |
|
|
Term
| what is the role of the homeobox gene? |
|
Definition
| this is involved in *segmental organization of the embryo in the *craniocaudal direction. |
|
|
Term
| what are the rules of 2's for the 2nd week? |
|
Definition
| 2 germ layers: epiblast/hypoblast. 2 cavities: amniotic cavity, yolk sac. 2 components to placenta: cytotrophoblast, syncytiotrophoblast. |
|
|
Term
| what are the rules of 3's for the 3rd week? |
|
Definition
| 3 germ layers (gastrula): ectoderm, mesoderm, endoderm |
|
|
Term
| what are the rules of 4's for the 4th week? |
|
Definition
| 4 heart chambers, 4 limb buds |
|
|
Term
| what are the embryologic derivatives from surface ectoderm? |
|
Definition
| adenohypophysis (rathke's pouch), lens of the eye, epithelial linings of the oral cavity, sensory organs of the ear, olfactory epithelium, epidermis, salivary, sweat and mammary glands. |
|
|
Term
| what are the embryologic derivatives from neuroectoderm? |
|
Definition
| brain (neurohypophysis, CNS tumors, oligodentrocytes, astrocytes, ependymal cells, pineal glands), retina, spinal cord |
|
|
Term
| what are the embryologic derivatives from neural crest (ectoderm)? |
|
Definition
| ANS, dorsal root ganglia, cranial nerves, celiac ganglion, melanocytes, chromaffin cells of adrenal medulla, parafollicular cells (C) of thyroid, schwann cells, pia/arachnoid, bones of the skull, odontoblasts, and aorticopulmonary septum. |
|
|
Term
| what are the embryologic derivatives from endoderm? |
|
Definition
| gut tube epithelium and derivatives (lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells) |
|
|
Term
| what are the embryologic derivatives from mesoderm? |
|
Definition
| muscle, bone, connective tissue, serous linings of the body cavities, spleen, cardiovascular structures, lymphatics, blood, bladder, urethra, vagina, eustachian tube, kidneys, adrenal cortex, skin dermis, testes, ovaries. |
|
|
Term
| what is the mnemonic for defects related to embryologic derivatives from mesoderm? |
|
Definition
| VACTERL: vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal defects, and limb defects. |
|
|
Term
| what does the notochord induce? |
|
Definition
| the ectoderm to form the neuroectoderm (neural plate, CNS+). its postnatal derivative is the nucleus pulposus. |
|
|
Term
|
Definition
| *intrinsic disruption which occurs during the embryonic period (weeks 3-8) |
|
|
Term
|
Definition
| *extrinsic disruption, occurs after the embryonic period |
|
|
Term
|
Definition
| absent organ due to absent primordial tissue |
|
|
Term
|
Definition
| incomplete organ development, primordial tissue present |
|
|
Term
|
Definition
| absent organ, despite present primordial tissue |
|
|
Term
| what is the teratogenic effect of ACE inhibitors? |
|
Definition
|
|
Term
| what are the teratogenic effects of etoh? |
|
Definition
| birth defects, mental retardation, FAS |
|
|
Term
| what are the teratogenic effects of alkylating agents? |
|
Definition
| absence of digits, multiple anomalies |
|
|
Term
| what is the teratogenic effect of aminoglycosides? |
|
Definition
|
|
Term
| what are the teratogenic effects of cocaine? |
|
Definition
| abnormal fetal development, fetal addiction, placental abruption |
|
|
Term
| what is the teratogenic effect of diethylstilbestrol (DES)? |
|
Definition
| vaginal clear cell adenoCA |
|
|
Term
| what are the teratogenic effects of folate antagonists? |
|
Definition
|
|
Term
| what are the teratogenic effects of iodide (lack/excess)? |
|
Definition
| congenital hypothyroidism or congenital goiter |
|
|
Term
| what are the teratogenic effects of lithium? |
|
Definition
| ebstein's anomaly (atrialized R ventricle) |
|
|
Term
| what are the teratogenic effects of maternal DM? |
|
Definition
| caudal regression syndrome (anal atresia to sirenomelia) |
|
|
Term
| what are the teratogenic effects of smoking/nicotine? |
|
Definition
| preterm labor, placental problems, IUGR, ADHD |
|
|
Term
| what are the teratogenic effects of tetracyclines? |
|
Definition
|
|
Term
| what are the teratogenic effects of thalidomide? |
|
Definition
|
|
Term
| what are the teratogenic effects of valproate? |
|
Definition
| inhibition of intestinal folate absorption |
|
|
Term
| what are the teratogenic effects of vit A excess? |
|
Definition
| spontaneous abortions, birth defects (cleft palate, cardiac abnormalities) |
|
|
Term
| what are the teratogenic effects of warfarin? |
|
Definition
| bone deformities, fetal hemorrhage, abortion |
|
|
Term
| what are the teratogenic effects of X-rays/anticonvulsants? |
|
Definition
|
|
Term
| what is the leading cause of congenital malformations in the US? |
|
Definition
| FAS = increased incidence of: congenital abnormalities, pre/post natal retardation, microcephaly, holoprosencephaly, facial abnormalities, limb discoloration, and heart/lung fistulas. mechanism may include inhibition of cell migration. |
|
|
Term
| when does diamniotic dichorionic twinning occur? |
|
Definition
| before day 3 - when the chorion is formed |
|
|
Term
| when does diamniotic monochorionic twinning occur? |
|
Definition
| between day 3 (when chorion is formed) and day 8 (when the amnion is formed). |
|
|
Term
| when does monoamniotic dichorionic twinning occur? |
|
Definition
| after day 8, when the amnion is formed. at this point, there is a risk for conjoined twins. w/this, 1 zygote splits evenly to develop 2 amniotic sacs w/a single common chorion and placenta. risk for: conjoined twins, who have 1 chorion and 1 amniotic sac |
|
|
Term
| what are the fetal components of the placenta? |
|
Definition
| cytotrophoblast: inner layer of chorionic villi (Cyto makes Cells). syncytiotrophoblast: outer layer of chorionic villi, secretes hCG (structurally similar to LH, stimulates corpus luteum to secrete progesterone during 1st trimester). |
|
|
Term
| what is the maternal component of the placenta? |
|
Definition
| the decidua basalis, which is derived from the endometrium. maternal blood is seen in the lacunae. |
|
|
Term
| what characterizes the umbilical arteries? |
|
Definition
| these return deoxygenated blood from the fetal internal iliac arteries to the placenta. |
|
|
Term
| what characterizes the umbilical vein? |
|
Definition
| this supplies oxygenated blood from the placenta to the fetus - drains into the IVC. |
|
|
Term
| what are the fetal arteries/veins derived from? |
|
Definition
| the allantois, which is formed from the yolk sac (@ 3 wks) and becomes the urachus |
|
|
Term
| what occurs with a patent urachus? |
|
Definition
| urine discharge from the umbilicus |
|
|
Term
| what occurs with a vesicourachal diverticulum? |
|
Definition
| outpouching of the bladder |
|
|
Term
| when does the vitelline duct (omphalomesenteric - connects yolk sac to midgut lumen) obliterate? what happens if those doesn't occur? |
|
Definition
| 7 weeks. vitelline fistula may occur: failure of the duct to close, meconium discharges from the umbilicus. meckel's diverticulum: partial closure w/patent portion attached to the ileum. there may be ectopic gastric mucosa = melena and periumbilical pain. |
|
|
Term
| what does the truncus arteriosus give rise to? |
|
Definition
| the ascending aorta and pulmonary trunk |
|
|
Term
| what does the bulbus cordis give rise to? |
|
Definition
| the R ventricle and smooth parts (outflow tract) of the L+R ventricle |
|
|
Term
| what does the primitive ventricle give rise to? |
|
Definition
| a portion of the L ventricle |
|
|
Term
| what does the primitive atria give rise to? |
|
Definition
| the trabeculated L and R atrium |
|
|
Term
| what does the L horn of the sinus venosus give rise to? |
|
Definition
|
|
Term
| what does the R horn of the sinus venosus give rise to? |
|
Definition
|
|
Term
| what do the R common cardinal vein and R anterior cardinal vein give rise to? |
|
Definition
|
|
Term
| what pathology is associated w/the truncus arteriosus? |
|
Definition
| transposition of the great vessels (failure to spiral), tetralogy of fallot (skewed AP septum development), and persistent TA (partial AP septum development). |
|
|
Term
| what is the eisenmenger complex? |
|
Definition
| a membranous septal defect which initially causes L->R shunting and then R->shunting |
|
|
Term
| what characterizes interatrial septum development? |
|
Definition
| the foramen primum (big space between atria) narrows as the septum primum grows down toward the dorsal endocardial cushions. as the septum primum grows down, a gap opens behind it: foramen secundum. the septum secundum grows down to meet the septum primum, closing the foramen secundum. there is some space left here in utero = foramen ovale, which usually closes soon after birth due to increased LA pressure. |
|
|
Term
| what is the mnemonic for fetal erythropoiesis? |
|
Definition
| Young Liver Synthesizes Blood = yolk sac (3-8 wk), liver (6-30 wk), spleen (9-28 wk), bone marrow (20 wk +). |
|
|
Term
| what is fetal vs adult Hb? |
|
Definition
| fetal: alpha 2 gamma 2. adult: alpha 2 beta 2. |
|
|
Term
| what are the 3 important shunts in fetal circulation? |
|
Definition
| umbilical vein -> liver *ductus venosus* (bypass hepatic circulation) -> IVC -> R atrium *foramen ovale* -> aorta (head+body) *ductus arteriosus* (lower body) -> aorta -> internal illiacs -> umbilical arteries. |
|
|
Term
| how does the infant's initial breathing close the heart shunts? |
|
Definition
| decreased resistance in the pulmonary vasculature = increased L atrial pressure = foramen ovale closure. increased O2 = decreased prostaglandins = closure of ductus arteriosus. |
|
|
Term
| what drug helps close the PDA? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| what does the prosencephalon become? |
|
Definition
| the telencephalon (cerebral hemispheres, lateral ventricles) and diencephalon (thalami, 3rd ventricle) |
|
|
Term
| what does the mesencephalon become? |
|
Definition
|
|
Term
| what does the rhombencephalon become? |
|
Definition
| metencephalon (pons+cerebellum), myelencephalon (medulla), and 4th ventricle |
|
|
Term
| what is seen in terms of lab work in neural tube defects while in utero? |
|
Definition
| elevated alpha feto protein (AFP) in amniotic fluid and maternal serum. increased AFP and acetylcholinesterase in CSF. |
|
|
Term
| what is associated w/anencephaly? |
|
Definition
| malformation of the anterior end of the tube, no brain/calvarium, elevated AFP, and polyhydramnios (no swallowing center in brain). |
|
|
Term
| what is associated w/holoprosencephaly? |
|
Definition
| little/lacking separation of hemispheres across midline; results in cyclopia, associated w/patau's syndrome, severe FAS, and cleft lip/palate. |
|
|
Term
| what are the 2 posterior fossa malformations? |
|
Definition
| chiari II: starts as communicating hydrocephalus, cerebellar tonsilliar herniation through the foramen magnum w/aquductal stenosis and hydrocephaly. often presents w/syringomyelia and thoraco-lumbar myelomeningocele. dandy-walker: most are non-communicating hydrocephalus, large posterior fossa, absent cerebellar vermis w/cystic enlargement of the 4th ventricle. can lead to hydrocephalus and spina bifida. |
|
|
Term
|
Definition
| enlargement of the central canal of the spinal cord. crossing fibers of the spinothalamic tract are typically damaged first = "cape like" bilateral loss of pain/temp sensation w/preservation of touch sensation. associated w/chiari II malformation. most common at C8-T1. |
|
|
Term
| what are the aortic arch derivatives? |
|
Definition
| 1: maxillary artery (first arch is MAXimal, branch of external carotid). 2: stapedial, hyoid arteries (Second is stapedial). 3: common carotid and proximal part of internal artery (C is 3rd letter of alphabet). 4: L - aortic arch, R - prox R subclavian artery. 6: L - proximal part of pulmonary arteries and ductus arteriosus (pulm, pulm-systemic shunt). |
|
|
Term
| what is the mnemonic for the branchial apparatus? |
|
Definition
| CAP (outside in): Clefts - ectoderm, Arches - mesoderm, Pouches - endoderm. |
|
|
Term
| what does the 1st branchial cleft develop into? |
|
Definition
| the external auditory meatus |
|
|
Term
| what are the 2-4th clefts obliterated by? |
|
Definition
| proliferation of the 2nd arch mesenchyme |
|
|
Term
| what is persistent cervical sinus? |
|
Definition
| a branchial cleft cyst w/in the lateral neck |
|
|
Term
| what are the 1st branchial arch derivatives? |
|
Definition
| *cartilage: meckel's - mandible, malleus, incus, spheno-mandibular ligament. *muscles: muscles of mastication - temporalis, masseter, lateral/medial ptyergoids, mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini, and anterior 2/3 of the tongue. *nerves: CN V2/3 (chewing). |
|
|
Term
| what is treacher collins syndrome? |
|
Definition
| 1st arch neural crest fails to migrate -> mandibular hypoplasia, facial abnormalities |
|
|
Term
| what are the 2nd branchial arch derivatives? |
|
Definition
| *cartilage: reichert's - stapes, styloid process, lesser horn of the hyoid, stylohyoid ligament. *muscles: facial expression - stapedius, stylohyoid, posterior belly of digastric. *nerve: CN VII (facial expression). |
|
|
Term
| what are the 3rd branchial arch derivatives? |
|
Definition
| cartilage: greater horn of the hyoid. muscles: stylopharyngeus. nerve: stylopharyngeus. |
|
|
Term
| what occurs w/a congenital pharyngocutaneous fistula? |
|
Definition
| persistence of cleft and pouch -> fistula between the tonsillar area and cleft in the lateral neck. |
|
|
Term
| what are the 4-6 branchial arch derivatives? |
|
Definition
| cartilage: thyroid, cricoid, arytenoids, coriculate, and cuneiform. muscles: 4th arch - most pharyngeal constrictors (cricothyroid, levator veli palatini), 6th arch - all intrinsic muscles of larynx, except the cricothyroid. nerves: 4th arch - CN X (superior laryngeal branch: swallowing), 6th arch - CN X (recurrent laryngeal branch: speaking). |
|
|
Term
| what do the branchial arches 3+4 form? |
|
Definition
| the posterior 1/3 of the tongue. |
|
|
Term
| what does the first branchial pouch develop into? |
|
Definition
| the middle ear cavity, eustachian tube, and mastoid air cells. |
|
|
Term
| what does the second branchial pouch develop into? |
|
Definition
| the epithelial lining of the palatine tonsil |
|
|
Term
| what does the 3rd branchial pouch develop into? |
|
Definition
| the inferior parathyroids (dorsal wings) |
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