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Vertebrate Embryolog
Exam 2
| Question | Answer |
|---|---|
| what type of cleavage do amphibians have | holoblastic, unequal radial holoblastic cleavage |
| what is the significance of the cortical rotation after fertilization | it initiates a series of events that lead to the formation of the gay crescent and axis determination |
| major events that occur during the mid-blastula transition | cell cycle becomes longer with the addition of G1 and G2, loss of synchronicity of cell division, due to exhaustion of maternally derived cell-cell controls mRNAs, and transcription of new mRNAs occurs |
| how are the three germ layers formed | Vg1 promotes endoderm fate, VegT, Nodal Eomes promote mesoderm fate, animal cap cells that do not receive any signals become ectoderm |
| show that dorsal blastopore lip in amphibian early gastrula has organizer activity | Speamann and Mangold experiments: transplanting DPL from a pigmented newt embryo to ventral side of an unpigmented embryo of a similar stage |
| what is Nieuwkoop center | specific region in the dorsal most vegetal hemisphere of blastula, capable of inducing the formation of the organizer |
| how is Nieuwkoop center formed | preferential distribution of bata-catenin in the dorsal embryo |
| what is the organizer | dorsal marginal cells located above the Nieuwkoop center, dorsal blastopore lip |
| how is the organizer formed | induced by signals emitted from the Nieuwkoop center, particularly the high concentrations of Xnr |
| major functions of the organizer | ability to initiate movements of grastrulaiton, ability to become dorsal mesoderm, ability to dorsalize the ectoderm into neutral ectoderm |
| major organizer proteins | Goosecoid, chordin, Noggin, Nodal related 3, follistatin, Cerberus, Dickkopf, Frzb, Tiki |
| what are the organizer tissues | pharyngeal endoderm, head mesoderm, notochord, and dorsal blastopore lip |
| Dorsal-ventral (DV) axis is determined by interaction of | BMPs and BMP inhibitors |
| Anterior-posterior (AP) axis is regulated by Wnt levels, which in turn is controlled by Wnt blockers such as | Cerberus, Frzb, and Dickkopf |
| ciliated cells, Nodal, Pitx2 are involved in | left-right axis determination |
| BMP | bone morphogenetic protein |
| functions of BMP4 | induces ectoderm to become epidermis, promotes development of ventral mesoderm and lateral mesoderm |
| major types of cell behaviors responsible for cell movement during gastrulation | epiboly, involution, convergence, expansion, |
| zebrafish good for vertebrate development | low cost, ease of maintenance, rapid development, large eggs produced |
| zebrafish cleavage | discoidal meroblastic |
| zebrafish embryo proper is derived from | deep cells |
| germ ring | thickening of margin of epibolizing blastoderm composed of epiblast and hypoblast cells |
| embryonic shield | thickened structure in the future of dorsal side of the embryo and formed by convergence and extension of the hypoblast |
| neural keel | precursor of the zebrafish nervous system |
| how are BMPs expressed | future mesoderm and animal hemisphere of the embryo |
| major steps in generation of neural tissue | neural plate, neural tube, regionalization of the neural tube, forebrain, midbrain, hindbrain, and spinal cord |
| four distinct stages of the primary neurulation | elongation and folding of the neural plate, bending of the neural plate, convergence of the neural folds, and closure of the neural tube |
| failure of neural tube closure in the anterior neural tube causes | anencephaly |
| failure of neural tube closure in the posterior neural tube causes | spina bifida |
| failure of closing both anterior and posterior neural tube leads to | rachischisis |
| forbrain | prosencephalon, gives rise to the telencephalon and diencephalon |
| midbrain | mesencephalon, gives rise to midbrain |
| hindbrain | rhombencephalon, gives rise to cerebellum and medulla |
| what does telencephalon consist of | olfactory lobes, cerebrum and hippocampus |
| what does diencephalon consist of | epithalamus, thalamus, hypothalamus, and retina |
| 3 molecules involved in the anterior-posterior axis determination of the neural tube | cerberus, Frzb, Dickkopf |
| notochord and shh play a crucial role in determining ventral fates of the neural tube | measurement of shh concentration gradient, transplantation experiments |
| what happens when shh function is lost | fusion of the brain and eyes, abnormal head development, leathal |
| how do paracrine factors affect anterior-posterior and dorsal ventral axis determination | at different concentration gradients, different transcription factors are activated |
| what are the first multipotent neural stem cells of the embryo | neuroepithelial cells in the single layered neuroepithelium |
| what are the other stem cells in the vertebrate CNS | radial glial cells |
| 3 major types of neural progenitor cells in the mammal cortex | ventricular radial glial cells, outer radial glia cells, and intermediate progenitor cells |
| ventricular radial glial cell can produce | neurons |
| outer radial glia cells and intermediate progenitor cells can produce | IP, gives rise to new neurons |
| what are the germinal regions of the CNS | ventricular zone and subventricular zone |
| what is neocortex | layer of gray matter in the cerebrum that is distinguishing feature of the mammalian brain |
| 3 zones of early mammal brains | ventricular zone, intermediate zone, marginal zone |
| neuron birthday | dividing precursor undergoes its final round of cell division to give rise to postmitotic neurons |
| how is the mammalian cerebral cortex formed | new born neurons and progenitor cells migrate from the ventricular zone on the process of radial glial cells to more superficial layers, built inside first outside last |
| interkinetic nuclear migration | movement of nuclei within certain cells as they go through the cell cycle |
| correlation between the number and complexity of folds of the neocortex and intelligence | more folds, higher intelligence |
| what cell type has been considered to play a major role in the formation of the folds | outer radial glial cells in the subventricular zone |
| major distinguishing developmental features of human brain | retention of the fetal neuronal growth rate during early childhood, high transcriptional activity of certain genes, presence of human specific alleles of developmental regulatory genes, loss of transcriptional regulators of specific genes |
| hypermorphosis | mechanism for retaining fetal neuronal growth rate beyond birth |
| symmetrical cell division | precursor gives rise to two cells of the same type or one intermediate progenitor cell to two neurons, either enlarge the stem cell pool or deplete the precursor cell pool |
| asymmetrical cell division | precursor produces two different daughter cells, maintain precursor cell population and produce a new cell type |
| neural crest cells | transitory group of cells that migrate from the dorsal neural tube to various regions to give rise to multiple types of cells |
| major cell types derived from the neural crest cells | PNS, pigmented cells, facial cartilage and bones |
| EMT | epithelial to mesenchyme transition |
| two major migration pathways of trunk NCCs | ventral pathways to give rise to the PNS, dorsolateral pathway become melanocytes |
| main functions of neurotrophic factors | survival, differentiation, and growth |
| who discovered the first neurotrophic factor | Rita Levi Montaicini |
| growth cone organization | central domain, body, and peripheral domain, lamellipodia and filopodia |
| distribution of microtubules and actin in growth cone | microtubules in body, actin mainly in peripheral domain |
| major events/molecules involved in growth cone dynamic movments | dynamics of actin and microtubules, focal adhesion proteins such as cadherins, integrins, and regulatory factors |
| major types of molecules affecting pathfinding of neuronal axons | cells adhesion molecules ad extracellular matrix proteins, permissive and promoting growth, repulsive molecules, attractive molecules |
| how neuronal axons find their targets | growth cone organization, dynamic behaviors, molecules that affect growth cone behaviors |
| major divisions of the mesoderm | chroda, paraxial, intermediate, and lateral plate mesoderm |
| major derivatives of each type of mesoderm | chordamesoderm; notochord, paraxial; somites, intermidate; urogenital, lateral plate; cardiovascular/extraembryonic membranes |
| major divisions of somites | sclerotome and dermomyotome |
| major derivative of sclerotome | cartilage of vertebrae and ribs |
| major derivative of myotome | skeletal muscles of back, intercostal muscles, limb muscles, and body wall muscles |
| major derivative of dermomyotome | dermis of the back, precursors of muscle and brown fat cell |
| lower level of BMP are important for specification of | paraxial mesoderm |
| noggin is involved in | antagonizing the BMP function |
| major pioneer transcription factors in presomitic mesoderm specificaiton | Tbx6, brachyury, and mesogenin |
| caudal progenitor zone | region in tailbud of vertebrate embryos that is made up of multipotent neruomesoderm progenitor cells; mainly responsible for elongation of embryo |
| major molecules involved in the formation of the somite from the PSM | Ra, Fgf8, Wn3a, notch |
| molecular pathway leading to the epithelialization and formation of the somite boundary | notch activates Mesp, Lfng, and Hairy which activates Eph in the same cells |
| molecular name of the molecular clock | oscillatory notch |
| how are different domains of each somite specified | location |
| what are the four myogenic proteins | MRFs, MyoD, Myf5, myogenin, Mrf4 |
Created by:
mlv39
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