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Terms in this set (41)
What are the general stages of development?
3 general steps to cleavage
Oocyte -> Morula -> Blastula (location of germ cells)
3 general steps of gastrulation
Blastocoel forms -> Blastopore -> Ectoderm/Mesoderm/Endoderm
Brief overview of blastula to gastrula
1) The embryo differentiates into half animal and half vejetal
2) Axis specification and rotation - dorsal set
3) Epithelial cells change shape and the blastopore forms (and yolk plug)
4) Cells rotate inward
5) Neural folds
6) Neural groove
7) Open neural tube
Ectoderm develops into _ and give an example of each
1) Outer surface - epidermal cells of the skin
2) CNS - neurons of the brain
3) Neural crest - pigment cell (melanocyte)
Mesoderm develops into _ and give an example of each
1) Dorsal - notochord
2) Paraxial - bone tissue
3) Intermediate - tubule cell of the kidney
4) Lateral - RBC
5) Head - facial tissue
Endoderm develops into _ and give an example of each
1) Digestive tube - stomach cell
2) Pharynx - thyroid cell
3) Respiratory tube - lung cell (alveolar cell)
What is mesenchymal condensation?
Becomes epithelium (ex. cartilage mesenchyme)
What is mesenchymal cell division?
Mitosis produces more cells - hyperplasia (ex. limb mesenchyme)
Mesenchymal cell death?
Cells die (ex. interdigital mesenchyme)
Cells move at particular time and places (ex. heart mesenchyme)
Mesenchymal matrix secretion and degradation?
Synthesis or removal of extracellular layers (ex. cartilage mesenchyme)
Cells get larger - hypertrophy (ex. fat cells)
Epithelium becomes mesenchyme - entire structure (ex. Mullerian duct degeneration)
Epithelium becomes mesenchyme - part of the structure (ex. chick hypoblast)
Epithelial shape change or growth?
Cells remain attached as morphology is altered (ex. neurulation)
Epithelial cell migration (intercalation)?
Rows of epithelia merge to form fewer rows (ex. vertebrate gastrulation)
Epithelial cell division?
Mitosis within row or column (ex. vertebrate gastrulation)
Epithelial matrix secretion and degradation?
Synthesis or removal of ECM (ex. vertebrate organ formation)
Formation of free edges (ex. chick ectoderm)
The ability of a single cell to divide and produce all the differentiated cells in an organism
Divide into most, or all, cell types in an organism, but cannot develop into an entire organism on their own
Cells that have the capacity to self-renew by dividing and to develop into multiple specialized cell types present in a specific tissue or organ
Terminally differentiated to form only one cell type e.g., a neuron
The point during development at which a cell becomes committed to a particular fate due to cytoplasmic effects or to induction by neighboring cells.
Process in which cells become specialized in structure and function
Similar building parts and plans for all organisms up to a certain point in development
What is the point of model systems and give an example?
To provide opportunities to study processes common to multiple species (ex. tetrapod limb development)
Diagram the two major mechanisms of cell determination and explain their general molecular basis
(1) American v. European
(2) Cell-autonomy v. Non-cell autonomy (signaling)
(1) Asymmetric segregation - daughter cells born differently (mRNA or protein are cytoplasmic factors/determinants)
(2) If the non-mRNA cell has the right receptors for the right signals, it undergoes signaling
(1) Symmetric division - sister cells become different as a result of different exposure to inducing signals after birth
Distinguish (experimentally) between cell fate specification, cell determined, and cell differentiation
(1) Isolation - 4 cell embryo -> 1 cell (IV signaling factors
(2) Ablation - if removed and the cell fails, they were at least determined; if fine, maximal is specification
(3) Transplant - homotopic or heterotopic graft
Explain what cytoplasmic maternally-contributed determinants are, and justify their importance during development
Determinants are contributed by mom and then localized in different regions of the cytoplasm due to: (1) features of the embryonic cleavage and (2) 3' UTR sequences allow mRNAs to bind to proteins that can then carry the mRNA along microtubules
What are the three proposed models of cell fate?
American, European, and Euromerican
General steps of cell fate
(1) Specification, (2) Determined, and (3) Differentiation
What are the 2 exceptions to the general steps of cell fate?
(1) Limb regeneration and (2) induce pluripotent stem cells (in vitro)
What does it mean (molecularly) when we say that a cell is "specified" to take on a particular fate?
It can still make a different fate if given the right signals
Fate vs. Commitment
Fate: What it wants to be
Commitment: When a cell or group of cells become "determined" or committed, they are irreversibly changed at the molecular level
Two cells (A and B) normally contact each other in a developing embryo. If you ablate (destroy) cell A, cell B takes on an abnormal fate. If you ablate cell B, the fate of cell A is unaffected. Which of the following explanations do these results indicate?
B's normal fate is determined by a signal from A; A's normal fate is determined by cytoplasmic factors
It will develop autonomously into a particular structure upon isolation, but it can be "re-specified" by getting with a "bad crowd"
Develops autonomously no matter what (comitted)
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