Embryology

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By: alhayagem (37 month(s) ago)

nice slides

By: Consultants (56 month(s) ago)

i would like to hoin your group

Presentation Transcript

ANIMAL DEVELOPMENT : 

ANIMAL DEVELOPMENT THE STAGES OF EARLY EMBRYONIC DEVELOPMENT

PREFORMATION vs EPIGENESIS: 

PREFORMATION vs EPIGENESIS

FERTILIZATION: 

FERTILIZATION Creates diploid zygote Triggers embryonic development The process: Sperm penetrates egg membranes, head is ingested, nuclei fuse. Egg’s metabolic machinery is activated, meiosis is completed. Egg raises barriers to entry of other sperm. Fertilization membrane lifts off egg--‘slow block to polyspermy’

Acrosomal, Cortical Reactions: 

Acrosomal, Cortical Reactions

Cortical Reaction: Fertilization Envelope: 

Cortical Reaction: Fertilization Envelope

After Fertilization: 

After Fertilization Membrane lifted off zygote

Cleavage Determinants: 

Cleavage Determinants Distribution of yolk Even distribution (isolecithal) Uneven distribution (telolecithal) Animal pole Vegetal pole Holoblastic cleavage (mammals, frogs, sea stars) Meroblastic cleavage (fish, birds, reptiles) Deuterostome pattern

Formation of a Blastula: 

Formation of a Blastula Cell division continues until a hollow ball of cells forms One cell layer thick Fluid filled space is a blastocoel Indentation of blastopore ends this stage

Events of Gastrulation: 

Events of Gastrulation Three primary germ layers are established. Basic body plan is established, including the primary body axes. As a result of the movements of gastrulation, cells are brought into new positions, allowing them to interact with cells that were initially not near them. This paves the way for inductive interactions, which are the hallmark of neurulation and organogenesis. 4. Archenteron may appear

Radial Cleavage: 

Radial Cleavage http://www.uleth.ca/bio/bio1020/images/star8.jpg Sea Star

Sea Star Development: 

Sea Star Development http://www.uleth.ca/bio/bio1020/images/star8.jpg Blastula

Gastrulation: 

Gastrulation archenteron

Poles, Cleavage: 

Poles, Cleavage

Frog Cleavage: 

Frog Cleavage

Frog Holoblastic Cleavage: 

Frog Holoblastic Cleavage http://www.uleth.ca/bio/bio1020/images/frog12.jpg

Frog Blastula: 

Frog Blastula http://www.uleth.ca/bio/bio1020/images/frog10.jpg

Gastrulation: 

Gastrulation http://www.uleth.ca/bio/bio1020/images/frog8.jpg archenteron

Neurulation: 

Neurulation http://www.uleth.ca/bio/bio1020/images/frog5.jpg

Rate of Cell Division: 

Rate of Cell Division

EARLY CLEAVAGE 2-64 cells: 

EARLY CLEAVAGE 2-64 cells

Morula Blastula: 

Morula Blastula 16-64 cells 128 cells Blastocoel 256 cells

Development in a Chick Embryo: 

Development in a Chick Embryo http://www.lawrence.edu/dept/biology/embryoatlas/stage18whole1.jpg

Neurulation in a Chick (24 hr): 

Neurulation in a Chick (24 hr) http://www.uoguelph.ca/zoology/devobio/24hrchck/24ck2.htm

Chick Embryo 72 hrs: 

Chick Embryo 72 hrs http://www.uoguelph.ca/zoology/devobio/72hrchck/72ckintr.htm