Term
| What is the zona pellucida? |
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Definition
| The clear membrane surrounding the ovum which the sperm has to cross for fertilisation. Then provides the capsule for the division of zygote cells. |
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Term
| What is the name of the diploid cell with in the zona pellucida post fertilisation? |
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Definition
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Term
| After mitotic divisions and compacting of the blastomeres, what structure is formed at 16 cells? |
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Definition
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Term
| Why is the compacting of blastomere cells within the morula important? |
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Definition
| Allows efficient cell to cell signalling and communication |
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Term
| In a morula, what do inner cells become? |
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Definition
| Tissue of the embryo- embryoblast |
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Term
| In a morula what do outer cells become? |
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Definition
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Term
| DAY 5 At which point does a morula become a blastocyst? |
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Definition
| The formation of a blastocoele from the production of fluid by the embryoblast cells before they become uni-polar within the blastcyst |
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Term
| DAY 6: At which point is the zona pellucida in development? |
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Definition
| Implantation of the Blastocyst (embryo pole first) allowing trophoblastic cells to come in contact with the uterus |
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Term
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Definition
| The changes made in the uterine lining in order to allow for the trophoblastic cells to invade. |
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Term
| WEEK 2: When the trophoblastic cells begin to invade the uterine lining, what are the 2 layers that initially develop? |
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Definition
Outer- syncitiotrophoblast
Inner- cytotrophoblast |
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Term
| What are the first two layers that the embryoblast develop into? |
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Definition
| Epiblast and hypoblast, forming a bi-laminar embryonic disc. |
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Term
| In what week does the amniotic cavity begin to develop and how? |
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Definition
| Week 2, differentiation of embryoblasts into amnioblasts which secrete fluid creating the cavity. |
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Term
| How is the exocoelomic cavity formed? |
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Definition
| Hypoblastic cells produce a membrane surrounding blastocoele |
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Term
| What happens in the lacuna stage of embryonic development? |
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Definition
| Syncitiotrophoblast cells continue to multiply forming the syncitium. Vaculoes begin to appear, which merge, increase in size and become lacuni. These eventually establish the maternal-utero circulation. |
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Term
| Human chorionic gonadotrophin is used for and formed by what? |
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Definition
| Used for pregnancy testing and produced by placental cells, 2 weeks after fertilisation. |
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Term
| What cavity surrounds the embryoblast cells sepertaing them from the trophoblastic cells other than the connecting stalk at the END OF WEEK 2? |
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Definition
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Term
| What occurs to the embryoblast at the beginning of week 3 in gastrolation? |
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Definition
| Becomes a tri-laminar disc from a bi-laminar disc. Epiblast forms the ectoderm, endoderm and the mesoderm. Hypoblast forms the extra embryonic ectoderm. |
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Term
| What forms in morphogenesis? |
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Definition
| A primitive streak and primitive node |
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Term
| What is a primitive streak? |
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Definition
| Central to the epiblast resulting from cells 'diving down' through to other layers. |
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Term
| What is the primitive node? |
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Definition
| Circular cephalic end of the primitive streak |
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Term
| What is diffrerent about the cell layers at the bucco-pharyngeal membrane and cloacal membrane? |
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Definition
| There is no mesoderm layer, tightly adherent. |
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Term
| What does the ectoderm layer form? |
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Definition
| Epidermis, central/peripheral nervous system and retina of the eye. |
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Term
| What does the endoderm become? |
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Definition
| Epithelial layers of the resp and GI tract, glandular cells (e.g. liver/pancreas. |
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Term
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Definition
| Connective tissue, muscle, heart, vascular system and reproductive organs. (all in between endoderm and ectoderm) |
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Term
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Definition
| Cells passing into the primitive streak and remaining in midline through endoderm. Signalling centre controlling development of midline structures. |
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