2: Animal Development Flashcards
production of new individuals w/o fusion of gametes
asexual reproduction
- unequal division of organism
- new individuals detach after dev
- prominent among cnidarians
budding
formation of a new individual from an aggregation of cells surrounded by a capsule (common in sponges)
gemmulation
“virgin birth”
dev of embryo from an unfertilized egg/ embryo where gametes failed to unite during fertilization
parthenogenesis
type of parthenogenesis:
- eggs formed by mitotic division
- occurs in some flatworms, rotifers, crustaceans, insects
diploid parthenogenesis
type of parthenogenesis:
- haploid ovum formed by meiosis
(may/not be activated by sperm)
meiotic parthenogenesis
animal in north america composed of entirely female populations; reproduce via meiotic parthenogenesis
whiptail lizards
reproduction through fusion of gametes; produced via meiosis (typically 2 individuals)
sexual reproduction
type of sexual rep: sexes are separate
dioecious
type of sexual reproduction: individuals have both male and female reproductive organs
monoecious
- female gamete
- nonmotile/large
- source of cytoplasm, nutrients for zygote
- produced in smaller numbers
ovum (egg)
- male gamete
- small/ motile
- produced in larger numbers
- genetic material is highly condensed
spermatozoon (sperm)
- union of egg + sperm
- egg activate, begins dev
- results in diploid zygote
fertilization
- early development
- orderly series of mitotic divisions
- number of cells inc; mass same
cleavage
smaller cells result of cleavage in early dev
blastomeres
zygote’s visible axis: yolk-rich end
vegetal pole
zygote’s visible axis: mostly cytoplasm w minimal yolk
animal pole
types of eggs based on yolk placement: minimal yolk distributed evenly
isolecithal
types of eggs based on yolk placement: moderate amount of yolk at vegetal pole
mesolecithal
types of eggs based on yolk placement: large amount of yolk at vegetal pole
telolecithal
types of eggs based on yolk placement: large amount of yolk at center
centrolecithal
types of cleavage based on yolk amount: large amounts of yolk present; cleavage incomplete
meroblastic cleaveage
types of cleavage based on yolk amount: small amount of yolk; cleavage complete
holoblastic cleavage
type of holoblastic cleavage:
embryonic cells arranged in radial symmetry around animal-vegetal axis
radial cleavage
type of holoblastic cleavage: blastomeres cleave at ~45 degree angles to the animal-vegetal axis
spiral cleavage
type of holoblastic cleavage: cleavage plane in one blastomere is rotated 90 degrees to other blastomere (seen in mammals)
rotational cleavage
type of meroblastic cleavage: cleavage confined to small cytoplasmic disc above yolk
discoidal cleavage
type of meroblastic cleavage: cleavage restricted to cytoplasmic rim of egg due to centrally located yolk
superficial cleavage
hollow cluster of cells
blastula
fluid filled cavity in blastula
blastocoel
formation of multi layered embryo from blastula thru rearranging of blastomeres
gastrulation
- result of invagination in gastrulation
- internal pouch
- “primitive gut”
- becomes animal’s digestive tract later on
archenteron
opening of archenteron
blastopore
in ___, the blastopore becomes the mouth
protostomes
in ___, the blastopore becomes the anus
deuterostomes
tissue layer that gives rise to specific organs and tissues; result of gastrulation
germ layers
where animals only have the ectoderm and endoderm
dipoblastic
where animals have all 3 germ layers (endoderm, mesoderm, ectoderm)
tripoblastic
body cavity completely surrounded by the mesoderm
- cushioning/ protection of gut
- hydrostatic skeleton in soft-bodied animals
coelom
animals that lack coelom
acoelomate
body cavity partially surrounded by mesoderm
pseudocoelom
coelom is formed by the mesoderm spitting; how coelom is formed in coelomate protostomes
schizocoely
sides of archenteron push outward, produce pouch-like compartment which pinches off; how coelom is formed in deuterostomes
enterocoely
mesoderm cells are deposited along the outer edge of the blastocoel in _______
pseudocoelomate protostomes
formation of organs from the different germ layers
organogenesis
sequence of 180 DNA base pairs that regulate embryonic development
homeobox
subset of homeobox genes that determine the animal’s body pain such as segmentation, limb formation, head-tail directionality
hox genes
layer that gives rise to skin and nervous system
ectoderm
layer that gives rise to notochord, muscular system, circulatory system, urinary/reproductive organs
mesoderm
gives rise to gut lining, urinary bladder, respiratory tract/pharynx, liver, pancreas
endoderm
forms above the notochord, eventually folding in on itself and forming neural tube
neural plate
cells that give rise to the nerves
neural crest
