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Step 1 9.16.12
Embryology I
| Question | Answer |
|---|---|
| Where is Sonic hedgehog produced and what is its importance? | produced at base of limbs in zone of polarizing activity. invovled in patterning along anterior posterior axis |
| Where is Wnt 7 produced and what is its importance? | produced at apical ectodermal ridges, necessary for proper dorsal ventra lorganziation |
| Where is FGF prodcued and what is its importance? | produced at apical ectodermal ridge. stimulates mitosis of underlying mesoderm. providing for lengthening of limbs |
| What is the importance of Homeobox (Hox) genes and what do their mutation lead to? | invovled in segmental oraganization of embryon in cranicaudal direction. mutation causes appendages to be in wrong place |
| What happens on Day 0 for embryo? | fertilization by sperm forming zygote, intiating embryogenesis |
| What is the major embryo landmark in the 1st week? | hCG begins after implatation of the blastocyst |
| What is the embryologic land mark for 2 weeks? | bilaminar disk forms (epiblast, hypoblast) |
| What is the embyologic landmark within week 3? | trilaminar disk forms, gastrulation. primitive streeak, notocord, mesoderm. neural plate begin to form |
| What are the key events of embryo week 3-8? | neural tube formed by neuroectoderm clsoes by week 4. organogenesis and very susceptible to teratogens |
| What are the embryologic landmarks fo week 4? | heart beats. upper and lower limb buds form |
| What is the landmark for week 8 of development? | fetal movement, fetus looks like baby |
| What is the development landmark for week 10? | genetalia have male/female characterstics |
| What is the orientation and parts of the alar and basal plates? | alar plate (dorsal) becomes sensory, basal plate ( ventral) becomes motor. same oreintation as the SC |
| What is the process of neural development of neural plate and notocord? | notocord induces overlying ectoderm to differentiate into neuroectoderm and fomr the neural plate |
| What is the embryologic fate of the neural plate and notocord? | neural plate gives rise to nerual tube and neural crest cells. notocord becomes nucleus pulposus of the intervertebral discs |
| What is the rule of 2's for week 2 of development? | 2 germ layers: bilaminar disc of epiblast and hypoblast. 2 cavities: amniotic + yolk sac 2 components of placenta: cytotrophoblast, syncitiotrophoblast |
| How does the primitive streak form and what does it directly give rise to? | epiblast invaginates to form it. cells from it form intraembryonic mesoderm, endoderm |
| What is the rule of 3's for week 3 of development? | 3 germ layers formed(gastrula): ectoderm, mesoderm, endoderm |
| What is the rule of 4 for week 4? | 4 heart chambers, 4 limb buds |
| What are the derivatives of the surface ectoderm? | adenohyphosis (Rathke's puch), lens, oral epiuthelium, sensory organs of ear, olfatory epithelium, epidermis, anal canal before pectinate line. salivary, sweat, mammillary glands |
| What is a cranipharyngioma? | benign Rathke's puch tumor with cholesterol crystals, calcifications |
| What are the derivatives of the neuroectoderm? | brain (CNS neurons, oligodendrocytes,astrocytes) retina, spinal cord |
| What are the derivatives of the neural crest cells? | ANS, dorsal root ganglia, CN, celiac ganglion, chromaffin cells of adrenal medulla, parafollicular cells of thyroid, schwann cells, pia and arachnoid. bones of skull, odontoblasts, aorticopulmonary septum. |
| What is a general picture of the derivatives of neural crest cells? | Think PNS and surronding structures, teeth (CREST toothpaste) |
| What are the derivatives of the endoderm? | gut tube epithelium(anal canal above pectinate line): liver, lungs, kidney, thymus, pancreas, parathyroid, thyroid follicular cells |
| What are the derivatives of the mesoderm? | muscle bone, CT, seroud linings of cavitties, spleen, CV strcutures, lymphatics, blood, bladder, urethra, vagina, kidsneys, adrenal cortex, skin dermis testes ovaries |
| What is a mnemonic for mesodermal defects? | VACTERL: vertebral defects, anal atresia, cardiac defects,tracheo-Esophageal fistula, renal defects, limb defects |
| What is the postnatal derivative of the notocord? | nucleus pulposus of IV disk |
| What is a malformation and when does it occur? | intrinsic disruption, poccurs during embryonic period (week 3-8) |
| What is a deformation adn when does it occur? | extrinsic disruption occuring after embryonic picture |
| What is an agenesis? | absent organ due to absent primordial tissue |
| What is a hypoplasia? | incomplete organ development, primordial tissue is present |
| What is an aplasia? | absent organ despite present primordial tissue |
| When are embryos most vulnerable to teratogens? | weeks 3-8 |
| What is the fetal effect of ACE inhibitors in pregnancy? | renal damage |
| What is the fetal effect of alkylating agents in pregnancy? | absence of digits, multiple anomalies |
| What is the fetal effect of aminoglycosides in pregnancy? | CN VIII toxicity (A MEAN GUY hit the baby in the ear) |
| What is the fetal effect of carbamazepine in pregnancy? | neural tube defects, craniofacial defects,fingernail hypoplasia, IUGR |
| What is the fetal effect of diethylstilbestrol in pregnancy? | vaginal cear cell carcinoma |
| What is the fetal effect of folate antagonists in pregnancy? | neural tube defects |
| What is the fetal effect of lithium in pregnancy? | Ebstein's anomaly (atrialized right ventricle) |
| What is the fetal effect of phenytoin in pregnancy? | fetal hydantoin syndrome: microcephaly, dysmorphic cranifacial features, hypoplastic features, cardiac defects, IUGR, mental retardation |
| What is the fetal effect of in tetracycline pregnancy? | discolored teeth |
| What is the fetal effect of thalidomide in pregnancy? | limb defects ( flipper limbs) |
| What is the fetal effect of valproate in pregnancy? | inhibtion of maternal folate absorbtion leads to neural tube defects |
| What is the fetal effect of warfarin in pregnancy? | bone deformities, fetal hemorrage, abortion, opthalmological abnormaties (no warfare on placenta, kepp happy with Heparin!) |
| What is the fetal effect of alcohol in pregnancy? | leading cause of birth defects and mental retardation. fetal alcohol syndrome |
| What is the fetal effect of cociane in pregnancy? | fetal addiction, placental abruption |
| What is the fetal effect of amokingin pregnancy? | preterm labor, palcental problems. IUGR, ADHD |
| What is the fetal effect of iodide lack or excess? in pregnancy? | congenital goiter of hypothyroidism |
| What is the fetal effect of maternal diabetes in pregnancy? | caudal regression syndrome (anal atresia), CHD, neural tube defects |
| What is the fetal effect of excess vitamin A in pregnancy? | extremely high risk for spontaneous abortion and cleft palate, cardiac abnormalities |
| What is the fetal effect of x rays in pregnancy? | microcephaly, mental retardation |
| What is fetal alcohol syndrome? | retardation, microcephaly, holoprosencephaly, facila abnormality, limb dislocation, heart and lung fistulas |
| What is the mechanism of dizygotic vs monozygotic twins? | dizygotic= 2 eggs separately ferilized. monozygotes come from 1 egg |
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tjs2123
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