fertilization
Begins with contact between egg and sperm, ends with transfer of paternal chromosomes into the egg to form a zygote
cleavage
the process ofd vision, single-cell zygote begins a series of organized, successive mitosis to produce a multicellular, hollow structured called the blastula; no growth of embryo
gastrulation
the period of cell movement; starts with the formation of a curved groove (blastopore) in the region formally occupied by the gray crescent
unfertilized egg
stage 1; appears as a large cell with a clear nucleus and nucleolus
gray crescent
stage 2; a region located opposite the site of sperm penetration, becomes the dorsal side, where gastrulation will begin
2 cell stage
stage 3; The result of the first cleavage event after fertilization
4-cell stage
stage 4; The result of a second cleavage event
16-cell stage
stage 6
mid cleavage
stage 8; characterized by continued irregular cleavage and intrusion of pigmented area over pale area
late cleavage
stage 9; cells in animal hemisphere are small and pigmented and extend and well down toward the vegetal pole
dorsal lip
stage 10; The region above the blastopore on the dorsal side of the amphibian embryo.
mid gastrula
stage 11; the groove of the blastopore and the dorsal lip have spread to form a circle around the small area of the remaining yolk
late gastrula
stage 12; Blastoporeformed, surrounding yolk plug, blastopore elevated to point of posterior axis of embryo.
zygote
fertilized egg
yolk
made of proteins and lipids
vegetable pole
yolky side
animal pole
dark colored
blastula
a multicellular, hollow structure produced after a series of organized successive mitoses
blastomere
each cell of the blastula
blastocoel
the central cavity of the blastula
blastopore
the opening though which the cells on the surface of the embryo begin migrating to the Indies (into the blastocoel)
dorsal lip
The region above the blastopore on the dorsal side of the amphibian embryo
yolk plug
the remaining yolk in which the dorsal lips forms a circle around
ectoderm
outer germ layer, the brain and spinal cord
mesoderm
middle germ layer, muscles, skeleton, urogenital organs, muscle layer, and outer walls of digestive and respiratory tracts
endoderm
outer germ layer; inner lining of digestive and respiratory tracts
archenteron
the cavity formed by the endoderm; primitive gut; replaces the blastocoel and will eventually form the lumen of the digestive tract
dueterostomes
blastopore will form anus opening first
organogenesis
processes by which the cells of the three primary germ layers form actual organ systems in the embryo
differentiation
cells express their different morphological and functional specializations
neural plate
the flattening of the neural ectoderm
neural folds
forms when the neural plate rolls up at the edges
neural groove
area between the neural folds
neural tube
formed when the neural folds eventually fuse together to form an enclosed, hollow structure, ultimately forms the brain and spinal cord
notochord
A flexible rod that supports a chordate's back
yolk plug
A group of large, nutrient-laden endodermal cells surrounded by the completed blastopore in an amphibian gastrula. These cells will be covered by ectoderm and end up inside the embryo.
stage 22
tail fin circulation
stage 21
mouth open, cornea transparent
stage 20
gill circulation
stage 19
heart beat
stage 18
muscular response
stage 17
tail bud
stage 16
neural tube
stage 15
rotation
stage 14
neural folds
stage 13
neural plate, dorsal flattening