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17 Cards in this Set
- Front
- Back
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The upper and lower regions of somites produce what parts of the body? |
•Upper region –Dermatome –Dorsomedial muscle cells –Ventrolateralmuscle cells •Lower region –Vertebrae and ribs |
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Give 3 examples of regulatory factors involved in somite differentiation and briefly describe each |
- Dermatome is directed to become dermis by neurotrophin-3from dorsal neural tube - MYOD / MYF5 -myogenic regulatory factors –activate muscle-specific genes–can convert non-muscle cells to muscle cells Sonic hedgehog and noggininduce sclerotomeformation- |
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What the primaxial and abaxial domain? |
–PRIMAXIAL DOMAIN -region around the neural tube, somite derived mesoderm - signals for development come from neural tube and notocord –ABAXIAL DOMAIN parietal layer of lateral plate mesoderm and some migratory somiticcells - signals for development come from lateral plate mesoderm - seperated by the lateral somitic fontier |
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Give 5 examples of muscle formed in the primaxial and abaxial domains, respectively |
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What innervates the epaxial muscles? What innervates the hypaxial muscle? |
-dorsal primary rami - ventral primary rami |
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What are the four developmental mechanisms? |
–Cell Differentiation –Pattern Formation –Morphogenesis –Growth |
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Describe differentition |
-the process of a cell changing from one cell type to another. •Most commonly this is a less specialised type becoming a more specialised type |
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What are limb buds derived from? |
- undifferentiated mesoderm cells covered by ectoderm |
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When does limb morphogenesis occur? |
4-8 weeks |
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What happens in the absence of the apical ectodermal ridge? |
–limb fails to develop –key signalling centre |
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What is polydactyly? What causes it? |
- extra digits - defects in mesoderm |
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What are the 3 components formed at week ~6? |
–Stylopod:humerusand femur –Zeugopod: radius/ulna and tibia/fibia –Autopod:carpels, metacarpals, digits, tarsals/metatarsals |
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What regulates the position of limbs along the craniocaudal axis? |
HOX genes |
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What is the role of T-box family transcription factors? |
–TBX-5 expressed in the upper limbs –TBX-4 and PITX1 in the hind limbs |
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At what stage do the digits become separated? |
day 56 |
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When and where do the primary centres of ossification form? |
long bones week 12 |
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Summarise the stages of bone development |
•Week 6: Cartilage models of bone form •Week 8: Ossification begins •Week 12: Primary centres of ossification in all long bones of limbs •Birth: Epiphyses still cartilaginous, secondary centres of ossification appear •Puberty: Growth plates close |
