 | Term | Definition |
| |
cleavage |
mitotic divisions |
| |
morula |
a solid mass of blastomeres that forms when the zygote splits |
| |
Inner Cell Mass |
morula inside blastocyst, The mass of cells in the blastocyst that ultimately give rise to the embryo and other embryonic structues (the amion, the umbilical vessels, etc.) |
| |
blastocoel |
inner fluid filled space in the blastocyst, The fluid-filled cavity that forms in the center of the blastula embryo. |
| |
trophoblast |
extra embryonic membranes, the membrane that forms the wall of the blastocyst in early development |
| |
In Vitro |
hormone stimulated egg maturation; eggs removed; sperm and eggs combined outside of mother; zygote returned and implanted in uterus |
| |
Differentiation |
when cells show observable (form, biochemistry etc...) signs that they have a new identity |
| |
development |
progressive (slow) changes that give rise to a multicellular organism |
| |
embryo |
Earliest stages in the development |
| |
Gastrulation |
blastocyst + gastrula; creates main tissue layers that form animal body |
| |
mesoderm, ectoderm, endoderm |
tissue layers |
| |
ectoderm |
skin, nervous system |
| |
mesoderm |
muscles, red blood cells, some internal organs |
| |
endoderm |
digestive tract, lungs |
| |
amnion |
inner membrane that contains amniotic fluid |
| |
chorion |
outer membrane that gives rise to placenta |
| |
placenta |
organ for gas, nutrient, and waste exchange between mother and embryo |
| |
umbilical cord |
connects embryo to placenta |
| |
identical twins |
single fertilized egg split into two embryos |
| |
fraternal twins |
two eggs released and fertilized in same cycle |
| |
external fertilization |
timing; usually aquatic ->allows sperm to travel |
| |
internal fertilization |
requires behavioral coordination |
| |
yolk sac |
contains nutrients for eggs |
| |
amnion |
fluid filled sac in eggs - protection |
| |
allantois |
waste storage in eggs |
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