2017 Embryology Revision Flashcards
(31 cards)
Embryology week 1
Explain what happens during days 3, 5 and 6
Day 3: morula is formed
Day 5: blastocyst is formed, via a cavity and cell layer being formed
Day 6: implantation into the uterine lining
Embryology week 2
- What 3 things happen on day 8?
- What forms on day 9?
- On day 13, what is there cavitation of and what does this form?
- Syncytiotrophoblast invades the endometrium
Bilaminar disc is formed (epiblast and hypoblast)
Amniotic cavity is formed - Primary yolk sac
- Cavitation of extraembryonic mesoderm
Forms chorionic cavity
Embryology week 3
Day 15
- What happens?
- What does this form?
- Where does it extend from and to?
- Indentation of ectoderm
- Forms primitive streak
- From primitive node to cloacal membrane
Embryology week 3 - days 14-19
What process occurs?
Gastrulation
Embryology week 3 - days 14-19 - gastrulation
- Where do cells migrate from?
- Where do they go?
- What is formed?
- Primitive streak
- Between the epiblast and the hypoblast
- Intraembryonic mesoderm
Embryology week 3 - days 14-19 - gastrulation
- What does ectoderm become?
- What does endoderm become?
- What does mesoderm become?
- Ectoderm: skin and neural tissue
- Endoderm: epithelial lining of gut, respiratory and urinary systems
- Mesoderm: muscle, bone, connective tissue, some organs and lining of body cavities
Embryology - somites
- Days?
- How do they appear?
- Nervous supply spread?
- Days 20-30
- Appear sequentially
- Each supplied by a single spinal nerve
Embryology- Neurulation
- Days?
- The notochord forms from what?
- What does the notochord form within?
- What does the notochord induce the formation of?
- What does the notochord become?
- Days 19-25
- Primitive node cells
- Mesoderm
- Neural plate
- Nucleus pulposus of IV discs
Embryology- neurulation
- What is neurulation?
- What is the simple 3 step process?
- What closes on day 25?
- What closes on day 27?
- Formation of neural tube
- Neural plate forms
Folds to form neural groove
Then neural tube forms - Cranial neuropore
- Caudal neuropore
Embryology - neural crest cell migration
- What happens to these cells?
- Name 4 things that these cells are involved in
- Name 3 things that can go wrong with defective migration
- Re-differentiate into other cell types
- Heart septation, face and skull connective tissues, GI tract ganglia and melanocytes
- Malformed face, nervous system absences and cardiac/gut defects
Embryology - neural tube defects
What is spina bifida?
Defective neural tube closure and anomalies of the covering tissues
Embryology- limbs
- Between which weeks?
- Which appear first and how long before the other?
- How are the digits formed?
- Weeks 4-8
- Upper limb buds 36 hours before lower
- Programmed cell death
Embryology- folding
- What are the 2 types of folding?
- What causes the head to fold?
- When does folding occur?
- Lateral folding and cephalo-caudal folding
- Rapid growth of brain and limited space available
- Weeks 3-4
Embryology - lateral folding
What is drawn around the entire disc?
Amniotic cavity
Embryology
What is the intraembryonic coelom and what does it become?
Cavity within mesoderm
Becomes body cavity
Embryology- teratogenesis
- Define teratogenesis
- When is the embryo at risk of a structural abnormality and why?
- When is the embryo at risk of a functional abnormality?
- What happens before week 3?
- Abnormality induced in developing embryo by harmful, foreign substances
- Weeks 3-8 because this is when cell division, organogenesis and midline union takes place
- Week 8 onwards
- Embryo will self-abort
Embryology- teratogens
Name 5 common teratogens and give 1 outcome for each
- Alcohol: fetal alcohol syndrome
- Vitamin A: cleft palate
- Maternal diabetes: heart and neural tube defects
- Rubella: deafness
- X-rays: spina bifida
Embryology - teratogens
Name 5 basic mechanisms of teratogens
- Mutations in DNA
- Interruption of DNA/RNA synthesis
- Failure of normal cell to cell interactions
- Interfering with cell differentiation
- Chromosomal abnormalities
Embryology- lungs
- When does the respiratory diverticulum first develop and what is it an outgrowth of?
- Its an out pouching of what?
- What does the trachea, bud grow into at 4-5 weeks?
- Which septum forms next?
- How many bronchial buds form on the right and how many form on the left?
- 4 weeks: outgrowth of foregut
- Outpouching of endoderm
- Splachnopleuric mesoderm
- Tracheo-oesophageal septum
- Right = 3
Left = 2
Embryology- lung bud division
- What are the 4 main divisions of the lung bud and what does each one produce?
- What happens at 6 months that allows the air spaces to inflate?
1. Primary - main bronchi Secondary - lobar bronchi Segmental bronchi Intrasegmental bronchi 2. Surfactant produced
Embryology- What are the steps of heart development and when does it start?
Mid week 3 Cardiogenic mesoderm develops Cords of angioblastic cells Forms 2 primitive heart tubes on either side When the embryo folds, the tubes fuse
Embryology- heart
- What turns the heart tube 180 degrees?
- When does the heart grow into (and get completely surrounded by) pericardium?
- What are the 2 pericardial sinus’s?
- With regards to the heart tubes, what happens at 20 days, 21 days and 23 days?
- Longitudinal folding
- Week 4
- Transverse pericardial sinus and oblique pericardial sinus
- 20 days: paired heart tubes
21 days: fusion
23 days: large single heart tube
Embryology- Primitive heart tube
- What 2 things are at the venous end?
- What 1 thing is at the arterial end?
- Name the 5 sections of the primitive heart tube from the venous end to the arterial end
- Right horn and left horn
- Aortic sac
- Sinus venosus
Atrium
Ventricle
Bulbis cordis
Truncus arteriosus
Embryology- primitive heart tube What do the following things become: 1. Sinus venosus? 2. Atrium? 3. Ventricle? 4. Bulbis cordis? 5. Truncus arteriosus?
- Sinus venosus = smooth wall of RA
- Atrium = rough wall of RA and LA
- Ventricle = rough part of LV
- Bulbus cordis = rough part of RV and outflow tracts for RV and LV
- Truncus arteriosus = roots of aorta and pulmonary trunk