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21 Cards in this Set
- Front
- Back
blastomere
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individual cells of the morula (from zygote to morula, these cells are blastomeres)
week 1 |
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morula
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made of 16-32 blastomeres. same size as initial zygote. as it enters the uterine cavity, it becomes the blastocyst.
week 1 |
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blastocyst
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the morula becomes the blastocyst as it enters the uterina cavity. it develops 2 layers: the outer cell mass (trophoblast) and the inner cell mass (embryoblast). the inside of the blastocyst is the blastocyst cavity.
after the zona pellucida disappears, the trophoblast becomes an outer layer, the syncytiotrophoblast) and an inner layer (the cytotrophoblast).the embroblast develops a layer of cells on the surface called the hypoblast. week 1 |
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zona pellucida
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protective covering of the zygote. covers the developing fertilized egg until the blastocyst reaches the uterine cavity. as this point it disappears, allowing the blastocyst to grow rapidly in size (prior to this, the zona pellucida inhibits growth in size).
week 1 |
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syncytiotrophoblast
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just prior to implantation, the trophoblast becomes two layers, the syncytiotrophoblast (outer layer) and the inner cytotrophoblast). this later invades the uterine wall and produces HCG (basis for pregnancy test).
week 1 |
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cytotrophoblast
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just prior to implantation, the trophoblast becomes two layers, the syncytiotrophoblast (outer layer) and the inner cytotrophoblast). this later provides new cells.
week 1 |
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hypoblast
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after the trophoblast becomes the outer syncytiotrophoblast and the inner cytotrophoblast and the blastocyst implants itself, the embryoblast develops a separate layer of cells around its surface, known as the hypoblast.
week 1 |
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first week of embryo
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zygote --> morula --> blastocyst --> implants into uterine wall
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epiblast
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during week 2, the blastocyst implants further into the uterine wall. the inner cell mass becomes the epiblast and the hypoblast, 2 distinct laters that touch each other.
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bilaminar germ disc
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aka the embryonic disc
this is where the epiblast and hypoblast meet. it is a disc like shape. above the bilaminar disk is the epiblast later. this develops a new cavity, the amniotic cavity, which fills with amniotic fluid. this cavity is lined with specialized epiblast cells called amnioblasts. below the bilaminar disc is the hypoblast layer. this layer develops a cavity, known as the exocoelomic cavity or primary yolk sac. cells lining the primary yolk sac produce a layer of loose connective tissue, called the extraembryonic mesoderm (sorrounds the yokk sac, amnion, and the bilaminar germ disc). week 2 |
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amniotic cavity
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the amniotic cavity develops above the bilaminar germ disc, out of the epiblast. the amniotic cavity is filled with amniotic fluid and lines with specialized epiblast cells called amnioblast.
week 2 |
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amnioblasts
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specialized epiblast cells that line the amniotic cavity
week 2 |
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exocoelomic cavity
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aka the primary yolk sac.
develops below the bilaminar germ disc, out of the hypoblast layer. it is lined by cells that produce a loose layer of connective tissue on the outside of the yolk sac, called the extraembryonic mesoderm (surrounds yolk sac, bilaminar germ disc, and amnion). week 2 |
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extraembryonic mesoderm
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a layer of loose connective tissues that surround the primary yolk sac, the bilaminar germ disc, and the amnion. it is produced by cells of the hypoblast layer, the line the primary yolk sac.
week 2 |
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extraembryonic coelom
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after the extraembryonic mesoderm forms, surrounding the yolk sac, bilaminar germ disc, and the amnion, vesicles appear in the mesoderm.
these vesicle coalesce to form the extraembryonic coelom. the extraembryonic coelon separates the extraembryonic mesoderm into 2 layers: -extraembryonic somatic mesoderm--applied to the trophoblast -extraembryonic splanchic mesoderm--applied to the yolk sac week 2 |
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extraembryonic somatic mesoderm
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the extraembryonic coelom separates the extraembryonic mesoderm into 2 layers:
-extraembryonic somatic mesoderm--applied to the trophoblast -extraembryonic splanchic mesoderm--applied to the yolk sac week 2 |
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extraembryonic splanchic mesoderm
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the extraembryonic coelom separates the extraembryonic mesoderm into 2 layers:
-extraembryonic somatic mesoderm--applied to the trophoblast -extraembryonic splanchic mesoderm--applied to the yolk sac week 2 |
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chorionic cavity
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after the extraembryonic membrane is separated into 2 laters by the extraembryonic coelom (the extraembryonic somatic mesoderm and the extraembryonic splanchnic mesoderm), the extraembryonic coelom is renamed the chorionic cavity. the growth of this cavity pinches off the primary yolk sac, forming the secondary yolk sac.
week 2 |
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secondary yolk sac
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the definitive yolk sac
formed where the emxtraembryonic coelom becomes the chorionic cavity. the primary yolk sac is pinched as the chorionic cavity pinches off a small piece of it. the secondary yolk sac eventually becomes the gi tract and its derivatives. week 2 |
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oropharyngeal membrane
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site of the future mouth.
forms from a section of the bilaminar disc, where a small circular area of hypoblast cells become attached to the overlying epiblast cells. opposite end of the disc from the cloacal membrane. week 2 |
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cloacal membrane
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site of the future anus.
forms from a section of the bilaminar disc, where a small circular area of hypoblast cells become attached to the overlying epiblast cells. opposite end of the disc from the oropharyngeal membrane. week 2 |