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DEVELOPMENTAL BIOLOGY
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HUMAN EARLY DEVELOPMENT
HUMAN EARLY DEVELOPMENT
HUMAN EARLY DEVELOPMENT
1. AN OVERVIEW OF HUMAN EARLY EMBRYOGENESIS
2. CLEAVAGE
3. BLASTOCYST, IMPLANTATION
4. GASTRULATION : Formation of the Primary Germ Layers,
5. NEURULATION : Making the Neural Tube
Notochord & Axis
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1. AN OVERVIEW OF HUMAN EARLY EMBRYOGENESIS
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AN OVERVIEW OF HUMAN EARLY EMBRYOGENESIS
http://en.wikipedia.org/wiki/Human_embryogenesis
AN OVERVIEW OF HUMAN EARLY EMBRYOGENESIS
Your subtopic goes here
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AN OVERVIEW OF HUMAN EARLY EMBRYOGENESIS
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2. CLEAVAGE
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CLEAVAGE
Cleavage: Functions & Events
Initial divisions of zygote to form the multicellular embryo
During cleavage the cells are called `Blastomeres`
They are rapid cell divisions with no intervening growth (G1 & G2) phases
Cells become smaller with time
Holoblastic Cleavage: cells are completely separate
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n & Compaction
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3. BLASTOCYST & IMPLANTATION
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Formation of the Blastocyst
Fluid begins to appear between blastomeres
Process is called `Cavitation`
Begins ~4 Days after fertilization
Produces `Blastocoele`: the fluid-filled cavity of blastocyst
http://www.utm.utoronto.ca/~w3bio380/allpdf.htm
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Hatching of the Blastocyst
Hatching occurs just prior to implantation
Embryo breaks through ZP due to proteases secreted by blastocyst
http://www.utm.utoronto.ca/~w3bio380/allpdf.htm
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Implantation
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Cell Adhesion Molecules & Implantation
L-selectin (Lymphocyte selectin)
-binds to sugar groups on extracellular matrix of endometrial cells
-weak adhesion; involved in initial adherence
-initiates events leading to trophinin expression by maternal cells
Trophinin
-once trophinin molecules appear on endometrial cells,
trophinin-trophinin binding occurs
-strong adhesion event
http://www.utm.utoronto.c