● Animal Development

○ Fertilization

■ The function of the cortical granules in relation to the vitelline envelope and plasma

membrane

○ Preventing polyspermy

■ Acrosomal enzymes eat away at the membrane

■ FAST block: species receptors change the membrane electrical potential by binding to

the bindin proteins on the acrosome...

● Na+ released into the cell making it positively charged

■ Fuse egg and sperm together → Ca+ wave to initiate slow bock

■ SLOW block: cortical granules fuse with membrane, goes back to negatively charged,

enzymes break connection between membrane and vitelline envelope, envelope

hardens & no bindin proteins for other sperm

■ Egg and sperm nuclei fuse → diploid zygote

○ Cleavage: embryo divides repeatedly into a small cluster of cells forming blastomeres (blastula)

■ Patterns of Yolk Distribution

● Holoblastic → whole embryo is dividing

○ Isolecithal → equal yolk distribution, most easily cleaved

■ Radial → new cells directly on top of each other forming new

layers

● Regulative development - new organism

■ Spiral → new cells form in furrows that are packed tightly

● Mosaic development - NO new organism

○ Mesolecithal → moderate distribution of yolk

■ Radial

● Meroblastic → part of the egg yolk remains undivided cluster of cells divide on

top of the yolk

○ Telolecithal → yolk concentrated at vegeta pole

○ Centrolecithal → large centrally located mass of yolk, most likely complete

cleavage

○ Blastulation: cleavage of the cytoplasm

○ Gastrulation: formation of germ layers & coelom by invagination

■ Germ Layers (outer to inner)