Embryogenesis and Development (3) Flashcards
Cortical reaction
When first sperm penetrates it causes release of calcium ion, which prevents other sperms from fertilizing the egg and increase the metabolic rate of resulting of diploid zygote.
Fraternal (dizygotic) twins
results from the fertilization of two eggs by two different sperm.
Identical (monozygotic) twins
results from the splitting of a zygote in two. Monozygotic twins can be classified by the placenta structures.
mono vs. diamoniotic –> sharing same amnion
mono vs. dichronic –> sharing same chorion
Indeterminate cleavage
results in cells that are capable of becoming any cell in the organism
Determinate cleavage
cells that are commited to differentiating into a specific cell type. or a whole organism
Morula
solid mass of cells seen in early development
Blastula (Blastocyst)
fluid-filled center called blastoceol and has two different structures: trophoblast, inner cell mass
trophoblast: becomes placental structures
inner cell mass: becomes the developing organism
Implantation
occurs during the blastula stage. Implants in endometerial lining and forms the placenta
Chorion
contrains chorionic vili, which penetrates the endometerium and create the interface between maternal and fetal blood. ( will develop into placenta later)
Allantois
involved in early fluid exchange between embryo and yolk sac ( occurs before placenta is established)
amnion
lies inside the chrion and produces amniotic fluid
Gastrulation
generation of three distancts cell layer.
Deutrosome vs. Protostomes
Deutrostomes (Humans)- blastophore will develop into anus first.
Protostomes- blastophore will develop into mouth first
Ectoderm
Mesoderm
Endoderm
Ectoderm- give rise to outer layer, and nervous system
Mesoderm- give rise to msucloskeletal and circulatory, and excertory system.
Endoderm- forms the epithelial lining of digesting and respiratory tracts, including the lungs.
Selective transcription
gene needed for the particular cell types are transcribed.
(pancreatic islet cells the genes are produce specific horomones are turned on, while these genes are turned off in other cell types.
Neurulation
Neural plate –> Neural fold –> Neural groove —> Neural tube
Neural tube
give rise to CNS
Neural crest cells
give rise to PNS
Teratogens
substances that interfere with development, causing defects or even death of the developing embryo.
Stages of zygote to gastrula
zygote - 2 - 4- 8- 16 Cell embryo - morula - bastula - gastrula
Determination
commitment to a specfic cell lineage, which may be accomplished by uneven segregation of cellular material during mitosis or with morphogens.
Morphogens
promote development down to a specific cell line. To respond to a specific morphogen, a cell must have competency.
Differentiation
refers to changes a cell undergoes due to selective transcription to take on characteristics appropriate to its cell line.
Stem cells
capable of developing into various cell types. Can be classified by potency.
Totipotent cells- able to differentiate into all cell types, including the three germ layers and placental structures.
Puripotent cells- able to differentiate into all three germ cell layers and their derivatives.
Multipotent cells- able to differentiate only into a specific subset of cell types.
Inducer
releases factors to promote the differentiation of a competent responder.
Autocrine
signals act on the same cell that released the signal
Paracrine
signals act on local cells
Juxtacrine
signals act through direct stimulation of adjacent cells
involve cell directly stimulating receptors of an adjacent cell.
Endocrine
signals act on distant tissues after travelling through blood stream.
growth factors
peptides that promote differentiation and mitosis in certain tissues.
reciprocal induction
if two tissues both induces further differentiation in each other.
Apoptosis
cell death via formation of apoptotic blebs that can be absorbed and digested by other cells.
Regenrative capacity
ability of an organism to regrow certain parts of the body
complete regeneration - lost or damaged replaced with identitcal tissues.
incomplete regenration - newly formed tissue isnt identitical in strucute or in function.
Senescence
result of multiple molecular and metabolic processes, most notably, the shortening of telomeres during the cell division.
Fetal hemoglobin (HbF)
has higher affinity for oxygen than adult hemoglobin HbA.
Placenta ( endocrine function)
secretes estrogen, progesterone, and hCG
umbilical arteries vs. umbilical veins
umbilical arteries - carry deoxygenated blood from fetus to placenta
umbilical vein - carry oxygenated blood from placenta to fetus.
Thre shunts:
Foramen ovale
Ductus arteriosus
Ductus venosus
Foramen ovale - connects the right atrium to the left atrium, bypassing the lungs
Ductus arteriosus- connects the pulmonary artery to the aorta, bypassing the lungs
Ductus venosus - connects the umbilical vein to the inferior vena cava, bypassing the liver.
Blood flow for the fetus: blood flow in ductus arteriosus is from the aorta to the pulmonary artery.
First trimester
organogensis occurs ( heart, eyes, gonads, limbs, liver, brain)
Second trimester
growth occurs, movement begins, face becomes distanctly human, digate elongate
Third trimester
rapid growth and brain development continue, and there is transfer of antibodies to the fetus
