Biol 441 exam 2 Flashcards
Curie’s principle
Effects have the same symmetry as their causes (and sometimes more)
Fucus brown alga symmetry breaking
Roots sprout on the darker side of the cell at the spherical 1 cell stage
Frog/salamander symmetry breaking
Point of sperm entry determines anterior-posterior (or dorsal-ventral) axis
Notochord is replaced by (in mammals and birds)
vertebral column
Notochord geometry
Stacked, inflated coins with large vacuoles
Notochord movement capabilities
Bending side to side
No anterior-posterior compression
Notochord convergent extension
Notochord cells extend processes sideways
They attach to each other and contract, stretching itself out
Notochord cells in reptiles, birds, and mammals
Last to leave the surface of the embryo, the epiblast, at Hensen’s Node
Somite formation location
Beside the neural tube at the paraxial mesoderm
Theories of somite splitting (2)
Active constriction
Decrease of cell-cell adhesion
Progenitor somites
Somitomeres
Theories of somite signalling (2)
Genetic mechanism similar to fly segmentation (Hox genes)
“Clock and wavefront” hypothesis
Somite subdivisions (4)
Dermatome
Myotome
Anterior sclerotome
Posterior sclerotome
Lateral plate mesoderm layer divisions (2)
Splanchnic layer
Somatic layer
Space in-between 2 layers of LPM
special feature in reptiles, birds, and mammals
Coelomic cavity
filled with coelomic fluid
in reptiles, birds, and mammals, is continuous with the space in-between the chorion and amnion, called the extraembryonic coelom
