Cleavage Flashcards
What is cleavage?
Series of cell divisions of zygote that occur without cell growth or separation
blastomere
daughter cells generated from cleavage divisions
What is a morula?
solid ball of cells created from early cleavage divisions
What is a blastula?
hollow fluid-filled ball of cells forme as water flows osmotically towards center or morula.
what is a blastocoel?
cavity formed in blastula. important for future development of organisms
karyokinesis
sepearation of chronosomes into two cells
cytokinesis
division of cytoplasm into 2 cells, facilitated by microfilaments
what are the two components of cleavage?
karyokinesis and cytokinesis
holoblastic cleavage
(complete cleavage) yolk doesn’t play much of an influential role because there isn’t much of it. Instead, cleavage can go all the way through the egg
happens in isolecithal and mesolecithal eggs
isolecithal
sparce, evenly-distributed yolk
mesolecithal
moderate vegetal yolk distribution, affects rate of cleavage
meroblastic cleavage
(incomplete cleavage) parts of egg are not cleaved because of the large amount of yolk
happens for telolecithal and centrolecithal eggs
telolecithal
dense yolk throughout most of the egg
centrolecithal
yolk in center of the egg
What is gastrulation?
series of movements of individual cells and sheets of cells that accomplishes at least three important developmental objectives
accomplishments of gastrulation
- Generates 3 germ layers
- Establishes bilateral symmetry
- Establishes new and unique cell interactions which influence future developmental events
What process of gastrulation develops germ layers?
ingression
What are cadherins?
family of cell-cell adhesion molecules that hold cells of blastula togehter as a sheet
aboral
side of developing organism away from mouth. like dorsal (as opp. to ventral)
