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18 Cards in this Set
- Front
- Back
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Diversification
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Zygote to MULTICELLULAR adult organism.
Requires division and formation of specialized cells in proper location. |
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Differentiation
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Process by which cells or tissues become DIFFERENT from one another.
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Does differential gene activity lead to irreversible turning off and on of genes?
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differentiation usually DOES NOT result in irreversible changes in the genome.
e.g. cloning of dolly. |
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Differential gene expression
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Different genes are turned on and off during development leading to specific genes being expressed in the differentiated cell.
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Pattern Formation
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Cells undergo differentiation at the proper time and in the proper location.
Teratomas occur from random differentation with NO pattern formation. |
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Lineage
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Developmental history of a cell. Can trace the developmental history of adult cells, tissues, and organs.
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Developmental Periods
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Fertilization
Week 1 - Cleavage and Implantation Week 2 - Embryonic period (bilaminar and trilaminar embryo, organogenesis, most vulnerable to teratogens). Weeks 9-38 - Fetal period (primarily growth, abortion, 24-25th week (viable fetus)). |
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Totipotential
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Able to differentiate into all cell types. e.g. Blastomeres and zygote.
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Pleuripotential
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Able to differentiate into many cell types. e.g. Stem cells and inner cell mass.
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Formation of Zygote
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1. Ovulation
2. Fertilizaiton 3. Zygote (Diploid cell and surrounded by extracellular layer composed of glycoproteins termed zona pellucida). |
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Gestational age
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Determine age based on time from LAST MENSTRUAL period.
40 weeks (used clinically) |
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Fertilization age
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Determine age based on time from FERTILIZATION
38 weeks (used in embryology) |
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Fertlization
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Occurs within uterine tube. If the egg is fertilized you will see two polar bodies.
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Cleavage of Zygote
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Rapid mitotic divisions of the zygote (cells get smaller and smaller and mass stays the same).
Forms blastomeres confined by zona pellucida (totipotential). Forms morula by the 3rd day. |
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Compaction
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Formation of tight junctions between outer blastomeres.
Process where you take blastomeres and make them different from each other. |
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Blastocyst formation
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Occurs 4 days after fertilization.
Subdivision of blastomeres into extraembryonic (trophoblast cells) and embryonic cells (inner cell mass cells). |
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Hatching of Blastocyst
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6th day of development.
Loss of zona pellucida. Formation of floating blastocyst. |
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Implantation
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Contact with endometrium
1. Trophoblast cells: - Forms two cell types = a) cytotrophoblast (actively dividing, surrounds blastocyst initially). b) synctiotrophoblast (nuclei does not divide, large synctium, highly invasive into endometrium) - produces protein and steroid hormones (hCG stops menstrual cycle and proteinases to promote invasion of the endometrial wall). 2. Inner cell mass cells: delaminate and form hypoblast layer facing blastocyst cavity. |
