BIOMG 1350 Chapter Notes - Chapter 22: Pupa, Morphogen, Anatomical Terms Of Location
13 Nov 2016
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The insect body is constructed as a series of segmental units: embryonic development: fertilization to larva, larva passes through 3 instars. Separated by molts in which it sheds old coat for larger one: end of 3 instars: pupates into pupa, pupa: metamorphosis-radical remodeling of body, after 9 days of fertilization: imago (adult fly) emerges, anatomy: Abdominal segments (a1 to a9: parasegments: half a segment out of register with traditional divisions. Drosophila begins its development as a syncytium: syncytial blastoderm. First 9 divisions migrate from middle of egg toward surface to form monolayer. After 4 more divisions, plasma membrane grows inward to enclose each nucleus, 6,000 separate cells. About 15 nuclei in extreme posterior, segregated few cycles earlier. Parts of sheet of cells tuck into interior to form gut, musculature, internal tissues. Series of indentations and bulges appear in surface of embryo. Genetic screens define groups of genes required for specific aspects of early.
