Embryology Flashcards
What time duration does the process of embryology refer to ?
The time from conception to gastrulation
What is a gamete
A germ cell with a haploid number of chromosomes - 23 single chromosomes in humans
What is meiosis
The process of cell division which results in the formation of a haploid germ cells from diploid receptors
What is a zygote
The earliest development stage formed by the combination of two gametes during fertilization
Describe the week by week process
Early events - Gametogenesis
First week - Fertilisation, zygote formation and implantation
Blastocyst develops
Second week - Bilaminar germ disc
Third week - Gastrulation (including formation of the neural crest)
Fourth to eighth week - Embryonic period
Describe the day by day process of early embryology
Day 1 - Fertilisation will occur
Day 2 - Cell division will occur until a small ball of cells known as a morula is produced
Day 3&4 - Morula begins to undergo some changes to form a blastocyst, with a blastocysts cavity and a thickened layer of cells at the other end
What is a morula?
A small ball of cells that is produced by cell division
How is a morula formed?
Morula is produced via the cell division of the zygote, and then produce a blastomere
What happens to the morula after cell division
The morula will undergo compaction and cavitation
This then leads to the formation of a blastocyst
What events are required for the formation of a blastocyst
Compaction and cavitation of the morula
Describe compaction
- After several cleavage divisions, the individual blastomeres will adhere
- This involves CAM’s expression and gap junction formation
- This allows for cell-to-cell adhesion and intracellular communication
Describe cavitation
- Formation of the ‘blastocyst cavity’ (Blastocele)
What is a pluripotent cell
A cell that has the ability to develop into a variety of cell and tissue types in response to specific environmental stimuli
What are the environmental stimuli needed to transform pluripotent cells into other cell types
- Cell-cell interactions
- Cell- matrix interactions
- Growth factors acting at an autocrine/ paracrine level
Give examples of pluripotent stem cells
Embryonic stem cells
Hematopoietic stem cells
Bone marrow (stromal) stem cells
What is the function of the trophoblast
Contacts with the endometrium of the uterus to facilitate implantation and the formation of the placenta
