This week in 206 I. Sea urchin fertilization thru gastrulation. II. Chick gastrulation thru...
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Transcript of This week in 206 I. Sea urchin fertilization thru gastrulation. II. Chick gastrulation thru...
This week in 206
I. Sea urchin fertilization thru gastrulation.
II. Chick gastrulation thru organogenesis.
III. Fungi fertilization and sporangium development.
Dr. Lloyd
DevelopmentSea urchinDeuterostomeIsolecithalHoloblastic cleavage
ChickDeuterostomeTelolecithalMeroblastic cleavage
Fertilization
cleavage
Blastulation & gastrulation
Organogenesis & pattern formation
Why do cells move in specific ways at specific times?How, why, and when do cells become specialized?
Sea urchin body plan
© 1997 Chris Patton, Stanford University
Fertilization
Sea urchin fertilization
acrosome
Cortical granules
Fertilization membrane
© 1997 Chris Patton, Stanford University
Fertilization
Holoblastic--cleaves completely through cell Isolecithal--evenly dispursed yolk.
Sea Urchin Cleavage and blastulation1st div. 3 div.
8 cell
blastula Hatchedblastula
Three types of morphogenetic movements duringgastrulation.
Gastrulation -2 types of morphogeneticmovements.1. Ingression of ~40 cells to formPrimary mesenchyme cells (PMC)Formation of mesoderm.
Gastrulation2. Invagination of cells at vegetal poleForms blastopore and archenteron-primitive gut
3 germ layersectoderm-skin and nervous system.mesoderm-bone, muscle, circ. system, internal organs.endoderm-stomach and guts.
archenteron
2nd ingression of cells to formSecondary mesenchyme
Primary mesenchyme
Together=mesoderm
archenteron
2nd invagination at animal poleto form mouth
Complete gastrula
EctoMesoEndo
Germ layers
Sea urchin larval development.
Sea urchin larva
NucleusCytoplasmYolk
Telolecithal-asymmetric
shellShell membrane
albumen
Meroblastic cleavage-part cleavage
1st div. 2nd 3rd
4th
Chick
~100,000 cells when egg laid.Epiblast - 3 germ layers
ectodermmesodermendoderm
Delamination
Ingression-mesoderm
Chick gastrulation.
Primitive streak-cells ingress-induced by hypoblast~blastopore
Notochord-induced by Hansen’s nodeSomites-muscle, bone
Embryo lifts off surface-3 layers-ectodermmesodermendoderm
Becomes brain
Sacs form around embryo
Fresh laid egg-blastodisc 13 hour egg
24 hour chick sections
33 hour chick sections
33 hour whole mount
48 hour 72 hour