L.19 Development 1 - Fertilisation and Neurulation Flashcards
L.O
- Recall the key cellular processes involved during early embryogenesis and development
- Describe the key events that take place during embryogenesis:
* Zygote to blastocyst development
* Bilaminar and trilaminar embryo formation (gastrulation)
* Neural tube formation - Describe the mechanism by which the embryo establishes a left-right axis
Cellular Processes involved during embryonic Development
- Proliferation
- Differentiation
- Interaction
- Movement
Cellular Regulation of cell identity
- Gene-expression
- Protein-expression
- microRNA
- Epigenetics
- Autocrine signalling (Secrete molecule that acts on self)
- Paracrine signalling (molecule acts on surrounding cells)
- Hormones (signals acting on other parts of body)
Morphogens and Morphogen Gradients
Morphogens:
- A molecule that instructs development
Organiser:
- A strcutre that sends a signal that effects surrounding cells
- Secretes a signal creating a concentration gradient
e.g neural tube [heft]
Embryonic development steps
Preimplantation Development:
1. Fertilisation occurs forming a diploid zygote
2. Zygote splits via clevage into many cells, forming a compact morula
3. Cell polarity is established and a cavity starts to form as fluids rushes into the embryo
4. Once a cavity is formed, it is now a blastocyst
5. The blastocyst contains an inner cell mass (ICM) (pluripotent cells) and a trophectoderm (multipotent cells)
Blastocyst Development and Hatching:
6. Differentiation occurs, ICM splits into Epiblast (pluripotent) and Hypoblast (Multipotent)
7. The embryo hatches outside of the Zona Pelucida
Blastocyst Implants into Uterin Wall:
8. Embryo adheres , and then attaches to endometrium lining
9. Embryo invades the uterin wall using trophoblast cells
10. Epiblast and Hypoblast form the Bilaminar Disk
11. Amniotic Cavity forms under the Bilaminar disk
Formation of Bilaminar Disk:
14. Trophectoderm cells surround the bilaminar disk, invading the epidermis forming the placenta
15. Primitive streak starts to form
Gastrulation and Germ Layers:
16. Epiblast starts to proliferate
17. Epiblast migrates through primitive streak, forming** 3 germ layers**
18. Difinitive ectoderm (top). Difinitive Mesoderm (middle). Difinitive Endoderm (bottom)
Nerual Plate formation:
19. Epiblast has crainial and caudal end
20. Primitive streak is on the caudal end, forms the primitive node
21. Primitive node contains Rotating Cilia which orientate LHS and RHS for signals
22. Epiblast proliferates again forming the Neural Plate
23. Neural Plate forms the Neural tube
Neurulation:
24. Epiblast thickens, elevates, folds forming neural folds and neural tube closes
25. Once Neural Tube closes surface ectoderm sits on surface of tube, notocord sits underneath
26. Brain and vertebral column regions form
CNS creation:
27. Surface ectoderm forms skin, hair and nails
28. Definitive ectoderm releases nerual crest cells to create PNS and melanocytes
29. Neural tube forms the CNS, brain and vertebral column
Organogenesis occurs:
30. The body plan is established, with formation of organs
Preimplantation Development:
- Fertilisation occurs forming a diploid zygote
- Zygote splits via clevage into many cells, forming a compact morula
- Cell polarity is established and a cavity starts to form as fluids rushes into the embryo
- Once a cavity is formed, it is now a blastocyst
- The blastocyst contains an inner cell mass (ICM) (pluripotent cells) and a trophectoderm (multipotent cells)
Blastocyst Development and Hatching
- Differentiation occurs, ICM splits into Epiblast (pluripotent) and Hypoblast (Multipotent)
- The embryo hatches outside of the Zona Pelucida
Blastocyst Implants into Uterin Wall:
- Embryo adheres , and then attaches to endometrium lining
- Embryo invades the uterin wall using trophoblast cells
- Epiblast and Hypoblast form the Bilaminar Disk
- Amniotic Cavity forms under the Bilaminar disk
Formation of Bilaminar Disk
- Trophectoderm cells surround the bilaminar disk, invading the epidermis forming the placenta
- Primitive streak starts to form
Gastrulation and Germ Layers
- Epiblast starts to proliferate
- Epiblast migrates through primitive streak, forming** 3 germ layers**
- Difinitive Ectoderm (top). Difinitive Mesoderm (middle). Difinitive Endoderm (bottom)
Nerual Plate formation
- Epiblast has crainial and caudal end
- Primitive streak is on the caudal end, forms the primitive node
- Primitive node contains Rotating Cilia which orientate LHS and RHS for signals
- Epiblast proliferates again forming the Neural Plate
- Neural Plate forms the Neural tube
[heft]
Neurulation
- Epiblast thickens, elevates, folds forming neural folds and neural tube closes
- Once Neural Tube closes surface ectoderm sits on surface of tube, notocord sits underneath
- Brain and vertebral column regions form
CNS creation
- Surface ectoderm forms skin, hair and nails
- Definitive ectoderm releases nerual crest cells to create PNS and melanocytes
- Neural tube forms the CNS, brain and vertebral column
Organogenesis
The body plan is established, and the formation of organs occurs
Female reproducive system hormones
- Control the reproductive stsem by cyclical changes
- Oestrogen and Progesterone make sure uterin lining is healthy
- Leutenizing hormone and FSH prep the oocyte for ovulation
