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29 Cards in this Set
- Front
- Back
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Where does the fusion of spermatozoon and oocyte occur? What is the fusion called?
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In the fallopian tube, called fertilization. Now called a Zygote, begins embryogenesis
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What is a zygote classified as, as it is able to form a whole organism?
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Totipotent blastomere
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When are most of the organs formed by? What does this signify the beginning of?
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8 weeks - the FETAL PERIOD
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In traveling the fallopian tubes, what keeps the embryo from attaching to the oviduct?
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The Zona pelliucida that coats it
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Where does fertilization occur?
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Oviduct
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What significant event occurs after the 3rd round of cleavage?
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Compaction of the cells into a 16-cell morula
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When does cavitation occur? How does it occur? What is its result?
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The trophoblasts secrete fluid to make a bastocoel (cavity) after the morula is formed, which is now a BLASTOCYST
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Describe the polarity created by cavitation of the morula.
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The blastocyst has an Embryonic pole (toward the cell mas) and Ab-embryonic pole (away from the cell mass)
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The 2 cells of the morula (Inner and Outer) each become what?
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Outer - placenta. Inner - inner cell mass - become embryo/yolk sac/amnion/allantois
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What is Gastrulation? What does it begin with?
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Begins with formation of primitive streak (from the epiblast) The process of bilaminer disc becoming trilaminer disc
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Which of the 3 trilaminer layers is formed 1st? How?
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The epiblast cells migrate inward into the primitive groove to DISPLACE the hypoblast cells there and make the ENDODERM
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Which of the 3 trilaminer layers is formed 2nd? How?
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The next layer of cells migrates between the endoderm and epiblast migrates into the prim groove to form the MESODERM
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Which of the 3 trilaminer layers is formed 3rd? How?
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The remaining epiblast cells (did not migrate) form the ECTODERM
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Where is Hensen's Node located? What does it become?
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It is near the ANTERIOR or ROSTRAL end, which becomes foregut/Head mesoderm (CNS) and NOTOCHORD
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What is the name of the DEEPEST area of the primitive groove, adjacent to Hensen's Node?
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Primitive Pit
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What is the Prochordal plate?
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small aggregation of cells that migrates as part of hte 2nd wave htru Hensen's node
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What is the primitive structure that becomes the oral cavity, located just rostral to the prochordal plate?
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The buccopharangyeal membrane
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How is the notochord formed?
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The primiitve streak regresses caudally and lays down notochord
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What is Neurulation? What other important formation occurs at this stage?
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Formation of the neural tube from the neural groove in the ectoderm. Also, the mesoderm forms the somites
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What protein supports development of the ectoderm? What inhibits it, thereby inducing development of NEUROectoderm?
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Noggin and Chordin, also Shh which develops the Neural Tube
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What is the TF secreted by neural crest cells? What does it do?
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Slug - promotes cell migration
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Which protein is thought to Help in neural fold fusion (closing the tube)
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Pax3
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Which genes help to specify the anterior-posterior positions of the embryo?
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Hox genes
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What is the term for the mesoderm lying laterally to the neural tube in early development? What is the next structure this gives rise to?
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Paraxial Mesoderm---Somites
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What are the 3 divisions of a somite?
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Sclerotome = vertebrae/IV discs
Myotome - trunk muscles Dermatome - Dermis |
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What is the term for the Mesoderm that is LATERAL to the PARAXIAL mesoderm (3 away from neural tube in early development) What does it give rise to
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Lateral Plate mesoderm - Splanchnic (wall of the gut)
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If the paraxial mesoderm does not become somites, what does it become?
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The head:
1 Somitomeres - jaw muscles 2 occipital somites - layrng/pharyng muscles 3 prechordal mesoderm - eye muscles |
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What genes can Counteract the inhibition by Shh genes? Where do they come from?
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Wnt genes - from the dorsal neural tube
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