Germ Layers Flashcards
Implantation
Blastocyst embeds in uterine lining
Inner cell mass
inner ball of cells
trophoblast
outer layer of cells
Bilaminar Embryo
Inner cell mass forms two germ layers
Epiblast
cell layer closer to trophoblast Forms embryo proper and amnion
hypoblast
cell layer farther from trophoblast. Forms yolk sac
germ layer
cell layers formed in early embryo. Create distinct tissues.
Amnion
a thin sac surrounding the conceptus proper.
Amniotic fluid
fluid filling amnion. Buffers force on embryo, expands as the embryo grows. Allows freedom of movement, prevents amnion from sticking to embryo, maintains body temperature.
water breaking
the rupture of the amnion
Yolk sak
doesn’t store yolk in humans. Makes blood for embryo until permanent blood production organs are produced.
Primitive streak
line down the middle of the embryo where cells group together. From the epiblast.
Trilaminar embryo
an embryo with three germ layers formed by gastrulation
gastrulation
a movement of cells that results in formation of three germ layers. Cells of the epiblast move through the primitive streak.
Ectoderm
remains of epiblast. Nervous system and outer layer of skin.
