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Slide3/28/12
BIO361Exam3
| Question | Answer |
|---|---|
| What is spina bifida occulta? | failure of two arches of a vertebra to fuse dorsally. dimple in skin or small hair over affected area. |
| What is spina bifida cystica? | Spinal cord bulges out dorsally and cyst covered with skin form on outside. Neurological disorders! |
| What is Anacephaly? | Failure of cephalic part of the neural tube to close, acrania & severe spina bifida. |
| T or F: Folic acid reduces spina bifida | True |
| Te ectoderm is divided to what three domains? | Epidermis, neural tube, and neural crest |
| The wall of the neural tube consists of one layer of what? | nueroepithelial cells that give rise to neuroblast and glioblast that develop into neurons and glial cells. |
| The anterior portion og the neural tube forms what? | THe BRAIN! |
| The posterior portion forms what? | THE SPINAL CORD! |
| The floor plate develops adjacent to the ______ and the motor neurons develop on both side of the ______. | notochord and floor plate |
| The extra floor plate is flanked by ____ sending out bundle of axons, and promoting the out grow of _____. | Efferent columns & commissural fibers |
| Removing notochord from neural tube left ventral tube cells unable to guide commissural fibers which demonstrates what? | Necessity and sufficiency of notochord for formation of floor plate and efferent coumns. |
| A signal released by the notochord induces what? | both floor plate and efferent columns directly and in gradient and concentration-dependant manner |
| High signal close to the notochord:______? | induces floor plate |
| Lower signal further away from the notochord:____? | induces efferent columns |
| A cascade of inductions from the notochord induces the ______, and floor plate in turn induces _____. | FLoor plate & motor clumns |
| The most important molecule in ventral patterning is ____/ | sonic hedgehog gene (Shh) |
| Shh is expressed in what? | notochord and floor plate |
| shh is necessary and sufficient for? | floor plate induction |
| Shh is a diffusable protein with concentration gradually _____ with ______ distance from notochord. | Decreasing with increased |
| Dorsal fate of neural tube is established by what proteins? | TGF-B superfamily |
| __and ___ in the ectoderm induce the roof plate to express__? | BMP4 and BMP7, BMP4 |
| BMP4 induces what? | a cascade of TGF-B superfamily proteins in adjacent cells. |
| The brain develops from the ____ part of the neural tube. | Cranial |
| What are ventricles? | Central canal that dilated to form fluid filled spaces |
| what are primary vesicles of neural tube? | Forebrain, midbrain, hindbrain |
| What are the 5 secondary vesicles of neural tube? | Telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon |
| Ectodermal placodes are transient thickenings of what? | the embryonic ectoderm |
| placodes that develop in head will form what? | part of sensory nervous system |
| T or F: All cranial placodes develop from thickening of head ectoderm? | True |
| By ____, placodal epithelium will form a vesicle. | Invagination |
| By ______, cells give rise to sensory neurons and secretory cells. | Delamination |
| what is the Principle of Reciprocal Interaction? | The ability of parts of a developing organ to exchange signals that coordinate their development in space and time. |
| what is an Example of the Principle of Reciprocal Interaction? | The eye originates from two major components: the optic vesicle, which give rise to the cup and retina, and the lens placode, which form the lens.The two rudiments exchange signals back and forth |
| The optic vesicle extends from the diencephalon and when it meets the head ectoderm, it induces the formation of a______? | Lens placode |
| THe lens placode invaginates to form what? | THe lens |
| The optic vesicle becomes the two-walled _________, whose two layers differentiate. | Optic cup |
| cells of the outer layer produce melanin pigment and ultimately become the what? | Pigmented retina |
| cells of the inner layer constitute the what? | Neural retina |
| Hans Spemann removed the ______ from one side of a frog tadpole and left the other undisturbed as a control | optic vesicle |
| What were the results of Hans Spemann experiment? | Normal eye detected on control side and no eye on operated side, therefore optic vesicle is necessary for lens formation |
| what is Heterospecific transplantation? | the epidermis from a large eyed donor species was transplanted over the optic vesicle of a small eyed donor species |
| What happened to transplantation of huge eye to small eye? | as the chimeric eye grew the lens slowed down in its growth while the optic cup grew larger than normal. |
| ____ activates a cascade of factors that mutually acivate one another to form eye field. | Pa6 |
| ____, __, and ___are expressed in the most anterior tip of the neural plate. | Six3, Pax6, and Rx1 |
| The separation of the single eye field into two bilateral fields depends upon the secretion of what? | The sonic hedgehog |
| If the sonic hedgehog gene is mutated, or if the processing of this protein is inhibited, what will occur? | The single median eye field will not split |
| What will result? | Cyclopia-a single eye in center of face |
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