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SGU: Development
Anatomy of Development
Question | Answer |
---|---|
Define embryo | Developing human during early stages of development |
Define zygote | following fertilization |
Define morula | 12-32 blastomeres. embryo enters uterine tube |
Define conceptus | Entire products of fertilazation, embryo and placenta |
Define primordium | beginning of discernable organ or structure |
Define fetus | After embryo/8 weeks |
Define capacitation | destabilization of acrosome head following ejaculation in vagina |
Describe fertilization | 1.sperm releases acrosin to digest zona pellucida 2. zona reaction occurs 3. fusion of PMs 4. oocyte completes meiosis II 5.formation of male pronucleus |
What is the pronuclei? | 2 haploid nuclei within fertilized egg before they fuse together. |
What is Dispermy? | two sperms paricipate in fertilization = triploidy |
What happens to triploid embryos? | appear normal but abort spontaneously. triploid infants that are born die soon. |
Define syngamy | Chromosomes of parents mix |
What are the results of fertilisation | restoration of diploid, sex determination, initiation of cleavage |
Define blastomere | dividing cells which becomes smaller following fertilization |
Define compaction: | following 8-cell stage the blastomeres aligns against e/o |
Describe the parts of a morula | embryoblast-inner cell mass, tropoblast-outer cell mass. |
What gives rise to the placent? | trophoblast |
Define blastocyst | zona pellucida degenerates and blastocyst cavity forms filled with uterine fluid |
Describe the layers of a trophoblast following implantation | Cytotrophoblast-inner layer of cells, syncytiotrophoblast-outer layer extending through endometrial epithelium |
What hormone forms the basis for a pregnancy test? | human chorionic gonadotropin released by syncytiotrophoblast |
What happens to the embryoblast following implantation? | forms embyonic disk with two layers-epiblast and hypoblast |
Define decidual cells | uterine cells filled with glycogen and mucous that degrade and provide a source of nurishment for synctiotrophoblast. |
Define amniotic cavity | a small cavity that appears in the embryoblast in the epiblast |
Where is the exocoelomic cavity and membrane found and what does this part become? | inside hypoblast, membrane=hypoblast. Becomes the primary umbilical vesicle/yolk sac. |
Define the extraembryonic coelom | Surrounds amnion and umbilical vesicle except where attached to chorion |
What is derived from the extraembryonic coelom? | chorionic cavity |
Define connecting stalk | where extraembryonic mesoderm traverses through the chorionic cavity to develop into umbilical cord. |
Define secondary yolk sac | primitive yolk sac formed when cells from the hypoblast migrate inside exocoelomic membrane. |
Define ectopic pregnancy | blastocyst implants in the uterine tube |
What constitutes the 'morning after pill' | high doses of estrogen to prevent implantation |
Describe gastrulation | bilaminar disk becomes trilaminar disk. The epiblast and hypoblast give rise to ecto, endo and meso-derm |
What are the steps of gastrulation | 1.primitive streak formation 2.epiblast cells migrate to primitive streak 3. epiblast cells invaginate spreading between epiblast and hypoblast 4. endo, meso and ecto-derm form from epiblast, hypoblast dissolves |
Describe the notochord formation | invagination of epiblast cells to form primitive pit, intercalate with hypoblast and proliferate and detach to form notochord |
What are the 3 divisions of the mesoderm? | lateral, intermediate, paraxial |
What does the lateral mesoderm give rise to? | visceral and parietal layer |
What does the intermediate mesoderm give rise to? | urogenital system |
What does the paraxial mesoderm give rise to? | somites-sclerotome, myotome, dermatome |
What are the two types of folding the embyro undergoes? | lateral-disc, cephalocaudal - head and tail |