Term
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Definition
| From fertilization through the eighth week of development |
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Term
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Definition
| In Utero development from after week 8 until birth. |
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Term
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Definition
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Definition
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Term
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Definition
| The haploid ovum (Secondary Oocyte) is fertilized bya haploid sperm to produce a diploid zygote. |
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Term
| 24 hours after fertilization - |
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Definition
| The first cleavage takes begins. |
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Term
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Definition
| An increase in the number of cells, but no increase in the size of the embryo. |
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Term
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Definition
| The cells produced by cleavage. Each new generation of cells is progressively smaller. |
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Term
| 3 days after fertilization - |
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Definition
| The structure that started as the Zygote reaches the16 cell stage. After this stage the developing embryo becomes a solid ball of cells known as a Morula (which means "Mulberry") |
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Term
| 5 days after fertilization - |
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Definition
| The morula has developed into the Blastocyst. This structure enters the Uterine cavity. |
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Term
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Definition
| The hollow ball of cells that enters the Uterine cavity. This structure contains hundreds of cell, but is approximately the size of the Zygote. |
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Term
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Definition
| this structure further differentiates into the Trophoblast and the Inner Cell Mass. |
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Term
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Definition
| The outer layer of cells that develops into the fetal portion of the placenta. |
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Definition
| The structure that allows for exchange of materials between the fetal and maternal circulation. |
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Definition
| The embryoblast. These cells will develop into the Embryo proper. |
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Term
| 6 days after fertilization - |
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Definition
| Blastocyst attaches to the lining of the Uterus. Implantation begins. The inner cell mass becomes oriented towards the endometrium. |
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Term
| 8 days after fertilization - |
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Definition
| The inner cell mass differentiates into two layers of tissue known as the Hypoblast (Endoderm) and the Epiblast(Ectoderm). This structure is known as the Bilaminar Embryonic Disc. The cell of the Trophoblast also begin to differentiate. Over the next few days, the Blastocyst will continue the process of implantation into the endometrium. |
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Term
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Definition
A layer of tissue that develops next to the amniotic cavity.
A layer of tissue that develops next to the blastocoele. |
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Term
| 16 days after fertilization - |
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Definition
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Term
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Definition
| The cells of the Epiblast begin to migrate and rearrange to form a shallow groove on the dorsal surface of the Epiblast. This structure is called the primitive streak, and will elongate to form the head and tail ends of the embryo. |
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Term
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Definition
The formation of body organs and systems.
All major systems will have begun to develop by week eight. |
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Term
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Definition
| The trilaminar germ disk that forms the embryo proper forms into a three dimensional cylindrical shape. Endoderm in the center, Ectoderm on the outside, and mesoderm in between. |
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Term
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Definition
Epithelium of many internal structures.
Ex. GI Tract, Urinary Bladder, Gall Bladder, Liver, Thyroid, Parathyroid, Thymus |
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Term
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Definition
| Cardiac, Skeletal and most Smooth muscle, Bone, Blood, Bone marrow, Dermis. |
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Definition
| Nervous System, Epidermis. |
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