Embryology Flashcards
What is a morula?
Bundle of cells 4-6 days.
What is a blastocyte?
6-10 days
Composed of both an Inner cell mass and Outer cell mass- called trophoblast.
What is the function of the placenta?
Organises transport of nutrients and waste from the embryo.
Do the mother and baby’s blood mix?
No, thin barrier separates
At how many days is a bilaminar embryo formed? What are the 2 layers called?
10-12 days.
Epiblast: Creates the embryonic endoderm, mesoderm and ectoderm.
Hypoblast: Formation of the endoderm and extraembryonic mesoderm.
What is gastrulation?
The process by which the embryo develops an axis.
3 Cell layers.
What is the key stage in gastrulation?
The primitive streak.
What occurs during the primitive streak?
Primitive groove develops and cells migrate through the groove to form the third layer; the mesoderm.
What is formed from continuous development of the primitive streak?
The nervous system.
What forms the central nervous system?
When the neural folds fuse to create the neural tube.
What are somites?
Lumps of cells associated with muscle formation.
How is the neural crest formed?
Formed when the neural tube closes off.
What is the role of the neural crest?
Forms the peripheral NS and is important in the formation of the face.
What does longitudinal folding of the embryo create?
The GI tract.
What does folding around the yolk sac of the embryo create?
The heart, liver and lungs.
Why is growth of the embryo so fast?
Folding of both sections occurs simultaneously.
When does the embryo become a foetus?
Week 9 onwards.
when does the neural tube form?
3-8 weeks
Name and explain the 2 types of embryonic stem cells.
Totipotent: Can specialise into any cell, even extraembryonic and placental cells.
Pluripotent: Can becomes any organ from within that germ group.
What is the difference between embryonic and adult stem cells?
Adult stem cells have committed lines
List some examples of what the ectoderm can give rise to.
Enamel!!
Brain and spinal chord
Skin
Mucus membranes
List some examples of what the mesooderm can give rise to.
Reproductive system.
Kidney and urinary system Connective tissue.
Muscle
List some examples of what the endoderm can give rise to.
Respiratory system
Alimentary canal.
What is the most important layer of the cell in terms of dentistry?
The ectomesenchyme: a fourth layer.
What does the ectomesenchyme give rise to?
Migration establishes tissues of the oral cavity e.g. muscles, periodontal tissues.
ALL EXCET ENAMEL.
The PNS
Sensory and autonomic nerves.
When does major tooth development occur?
6-8 weeks.
