Lecture 26 Development II

Lecture 26 Development II - Lecture 26 Development II I)...

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Lecture 26 Development II I) Meroblastic cleavage (e.g chicks) a. Gastrulation: layers of cells on top of yolk FIGURE 47-11 b. Organogensis: lateral folds pinch embryo away from yolk FIGURE 47-13 II) Cytoblastic Determinants a. Polarity (diagram) - Grey Crescent forms opposite side of sperm entry; results from movement of pigmented cells moving towards site of spermy entry determiner 2 axes: dorsal-ventral & left vs. right FIGURE 47-7 b. Grey Crescents- Confers “Potipotency” (i.e. can make whole embryo) i. Therefore: 1 st cell division is perpendicular to Grey Crescent “indeterminant” that is each daughter cell can make whole embryo! ii. Thus, Non-uniform distribution of regulatory components (mRNA’s etc.) throughout egg cytoplastm (specific parts i.e grey crescent repons. Diff. part) III) Fate Maps: Blastula cells “fated” (determined) to become particular cell types FIGURE 47-21 a. Early Gastrula Transplants (done on neut) i.
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Lecture 26 Development II - Lecture 26 Development II I)...

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