Embryology Flashcards
(86 cards)
Homologous
Arises from the same evolutionary path, from a common ancestor
Analogous
Arises from convergent evolution, a structure that performs the same function in two different organisms
Homoplastic
Two structures that look similar
Cleavage
Rapid cell division - no growth between division - until a solid ball of cells form called a morula. First step in embryo development.
Blastula formation
Formation of a blastula. Second step in embryo development.
Blastula
Hollow ball of cells (means “bud”)
Blastocoel
The empty space within a blastula. Round and even in microlecithal organisms, slightly squished in mesolecithal ones, flattened in macrolecithals.
Gastrulation
Rearrangement of cells within embryo, with outside migrating inside and differentiation of the three germ layers
Blastopore
The hole formed in blastula (the first hole), through which ectoderm cells migrate to the inside of the cell to form the endoderm.
Morula
Solid ball of cells formed from cleavage. Means “little berry”
Protostome
An organism where the blastopore becomes its mouth
Deuterostome
An organism where the blastopore becomes its butt-hole
Archenteron
“First gut”, becomes the gut lumen, formed as ectoderm migrates in the blastopore to form the endoderm, squishes up the blastocoel until the blastocoel disappears
Mesoderm
“Middle skin” - middle layer of embryonic cells
Ectoderm
“Outer skin” - outside layer of embryonic cells
Endoderm
“Inside skin” - inner layer of embryonic cells
Yolk plug
The slow division and movement of large yolk-filled cells in mesolecithal organisms create a “plug”-like structure as gastrulation occurs
Vegetal pole
In mesolecithals, the yolk-laden, slightly fatter end of the embryo
Animal pole
In mesolecithals, the smaller, pointer end of the embryo
Embryonic origin of notochord
Mesoderm
Neurulation
Formation of neural tube. Neural plate ectoderm sinks down and forms a neural groove surrounded by neural folds. The folds then come together to form a neural tube. Anterior end of neural tube swells to become brain
Neural plate ectoderm location?
Dorsal side of ectoderm
Neural crest cells origin
Neural plate ectoderm – forms off of neural folds, highly mobile cells
Which end of the neural tube swells to become the brain?
Anterior (front)
