Lab 13: Animal Embryology and Development

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Lab 13 Animal Embryology and Development
http//www.vifishandwildlife.com/Education/FactShe
et/Images/Diadema1.jpg http//www.coldwaterimages.
com/img/enc_hydro0.JPG
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Meiosis in animals occurs in the cells of the
reproductive organs (gonads ovaries and testes).
Fertilization sperm (N) fuses with egg (N) to
produce zygote (2N).
Gametes contain half the number of chromosomes
(N, haploid) as the parents cells (2N, diploid).
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Embryology is the study of the development of the
fertilized egg (zygote) through cleavage
(mitotic cell divisions), and differentiation.
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Sea Urchin Embryology
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A1
A1. Unfertilized egg. A2. Fertilized egg with
fertilization membrane. B. 2-cell stage. C.
8-cell stage. D. 16-cell stage. E. 32-cell stage.
F. Blastula stage
http//www.bio.davidson.edu/courses/GENOMICS/metho
d/UrchDev.html
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Sea Urchin Embryology
Middle Gastrula
Early Gastrula
http//www.bio.davidson.edu/courses/GENOMICS/metho
d/UrchDev.html
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Sea Urchin Embryology
Pluteus larvae. Sea urchin develops within a few
days. The pluteus larvae swim and feed
independently until it settles down and
metamorphoses into an adult.
http//personal.denison.edu/romanol/images/Larva.
jpg http//www.stanford.edu/group/Urchin/GIFS/bw-p
luteus.jpg http//www.ac.wwu.edu/iws/images/echin
oderm/pluteus.jpg
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Fertilization (p 20)

• External Fertilization both eggs and sperm are
  shed into the surrounding medium and the sperm
  cells swim or are carried by water currents to
  the egg cells.
• Limited to animals in aquatic environments
  (examples fish, frogs).
• Uncertain method because sometimes the sperm
  never find the eggs.
• Large numbers of sperm and eggs are released to
  increase chances of fertilization.

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Fertilization (p 20)

• Internal Fertilization- the egg cells are
  retained in the reproductive tract of the female
  until after they have been fertilized by the
  sperm (which are inserted into the female by the
  male).
• Sperm swim in fluid inserted by male into the
  female reproductive tracts (seminal fluids).
• Fertilized egg is either released by the female
  or held within the females body until embryonic
  development has been completed.
• Fewer eggs are released during reproductive
  season because there is a better chance of sperm
  reaching the egg.

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Embryo Development (p 20)

• Requirements for development

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