Embryology Flashcards
What three processes get an entire complex organism from a single cell
Growth
Differentiation
Morphogenesis
What is the process in which unspecialized cell or stem cells acquire specialized characteristics and functions to become distinct cell types with specific roles?
Differentiation
Define morphogenesis
the process by which tissues, organs and organisms acquire their characteristic shape and structure during development.
* position determines fate ie cells find position before they specialize
What 3 processes help determine shape
Motility- cells move and change shape
Induction- interaction between cells
Apoptosis- cell death
What are the 2 states which cells exist in the early embryo
Epithelial cells- tightly connected in sheets or tubes
Mesenchymal cells- unconnected and operating as independent units
What is the difference between reciprocal and sequential inductive events
Reciprocal- involves a bidirectional signaling; signals from one tissue induces changes in the other tissue and vice versa
Sequential- involves a linear progression of developmental events; one event triggers the next in a predetermined sequence
What 4 events are involved in the formation of the crystalline lens
- Lens placode formation
- Lens vesicle formation
- Differentiation of lens fiber cells
- Formation of lens capsule and zonules
Importance of apoptosis during development
Tissue patterning and morphogenesis
Removal of unwanted or defective cells
Definition of induction
The process by which one group of cells influences the fate, behavior or differentiation of neighboring cells
What is the embryonic and foetal period?
Embryonic -from fertilization to the end of week 8 of development, initial formation of organs
Foetal- week 9 to 36 (2nd and 3rd trimester), developing of organs
Give the 5 main stages of fertilization in the oviduct
- Sperm-egg interaction (sperm binds to zona pellucida)
- Fusion of genetic material
- Activation of egg
- Prevention of polyspermy
- Formation of zygote
Define fertilization
Process by which a sperm and egg cell fuse to form a single diploid cell called a zygote.
Marks the beginning of embryonic development
Give the stages of somatic cell nuclear transfer (cloning)
- Enucleation of egg cell
- Nuclear transfer of somatic cell into egg cell cytoplasm
- Embryo culture in a lab to develop a blastocyst
- Implantation of embryo or harvesting of stem cell
What causes Leber’s optic atrophy
Mutation of genes encoded by mitochondrial DNA
Symptoms of LHON/ Lebers optic atrophy
Blurring of central vision
Desaturation of colour
Optic nerve damage
Describe the processes cleavage and compaction
Cleavage- division of zygote into smaller cells known as blastomeres. Occurs without an increase in the overall size of the embryo
Compaction- cell to cell adhesion and morphology that result in the formation of a tightly adherent group of cells. Typically occurs around the 8to16 cell stage
Describe the process of cavitation
At the 16cell stage(morula), a blasteol (fluid-filled cavity) is formed within the ball of cells forming a blastocyst
Difference between trophoblast and embryoblast
Trophoblast- outer cell mass. Will form foetal part of placenta and other extraembryonic tissue
Embroblast- inner cell mass. Forms the actual embry and some extraembryonic tissue
Define implantation
process by which blastocyst attaches to and embeds within the lining of the uterus (endometrium) in preparation for further development
Differentiate the terms 1. Blastomere 2. Morula 3. Blastocyst 4. Blastocoel
- Blastomere- individual cells resukting from cleavage division
- Morula- solid ball of blastomeres
- Blastocyst- advanced stage with a fluid filled cavity and distinct cell populations
- Blastocoel- fluid filled cavity within the blastocyst
Define zygote
Cell formed by the fusion of two gametes ie sperm and egg cells
