Embryology Flashcards
Generalized Stages of Development
Fertilization
Cleavage
Blastulation
Gastrulation
Neurulation
Organogenesis
Vegetal Pole
end of egg where most yolk is concentrated
Opposite of animal pole
Animal Pole
end of egg where least yolk is concentrated
Divide more rapidly than vegetal pole
opposite of vegetal pole
Cleavage
Cell Divides to produce blastula, how it divides
TWO KINDS:
Holoblastic and Meroblastic
Holoblastic
Whole zygote divides
low amount of yolk
Echinoderms, mollusks, flatworms
Meroblastic
Part of zygote divides
high amount of yolk
fish, reptiles, birds
Blastomere
Each new cell resulting from the division
16-32 cells = Morula
64 cells = Blastula
Blastula
Hollow sphere of cells
SAME size as zygote
Center cavity = Blastocoel
Types of eggs
Isolecithal or Telolecithal
YOLK DOES NOT DIVIDE, CELLS AROUND YOLK DIVIDE
Isolecithal
Small amounts of yolk that is evenly distributed
Sea stars (Echinoderms)
Telolecithal
large amount of yolk that is concentrated at one end
Chicken and Frog
Gastrulation
Migration and specialization of cells
Blastula -> Gastrula
formation of germ layers
Archenteron = primitive gut
- opens to outside via blastopore
Multilayered embryo
Protosome
mouth is the first opening formed
Deutersome
Anus is the first opening formed
