Chapter 1 Flashcards
(21 cards)
Primary germ layers
Ectoderm
Mesoderm
Endoderm
Embryogenesis
Stages of development b/w fertilization and hatching (birth)
Blastopore
Dimple expands to a ring (mesoderm)
-during Gastrulation
6 processes of embryogenesis
Fertilization, cleavage, gastrulation, organogenesis, metamorphosis, & gametogenesis
Fertilization
Involves fusion of the mature sex cells, sperm & egg (gametes)
Cleavage
Series of extreme rapid mitotic divisions immediately after fertilization
Blastomeres
Enormous volume of zygote cytoplasm divided into numerous mini cells
[during cleavage]
Blastula
Blastomeres formed a sphere
[end of cleavage]
Gastrulation
- Mitotic rate slows down & blastomeres undergo dramatic movements & change their position
- three germ layers: results
Organogenesis
Once germ layers are established, cells interact w/ one another and rearrange themselves to prod. tissues and organs
[migrating cells, precursor blood, lymph, pigment, gamete cells]
Metamorphosis
Change an organism goes through to become a sexually mature adult
-germ cells
Gametogenesis
Development of gametes, not complete untill maturity
Blastocoel
Fluid filled cavity in animal pole. Important for allowing cell movements to occur during gastrulation
Notochord
- Where organogenesis begins
- Rod of mesodermal cells, signals ectodermal cells above to form tube
Neurula
Stage in which embryo formed a tube and have CNS
Neural tube
Future epidermal cells of back
Somites
Mesodermal tissue adjacent to the neural tube & notochord becomes segmented
-muscle, vertebrae, dermis
Fertilization & egg activation
Gray crescent (cortie cytoplasm shifts)
Preformationism
The idea that organisms develop from miniature versions of themselves
Ex Leeuwenhoek, malpigni
Epigenesis
The idea that animal development features an embryo thats influenced by external and internal environment, forms structure not present in gametes
Ex wolff
Recapitulation
Ontongeny (dev) recapitulates phylogeny (history)
Ex Haeckel
