Embryology Flashcards
What is morphogenesis?
The process of the cell changing shape
Where does fertilisation normally occur?
In the fallopian uterine tube - the ampulla
What do endoderm cells become?
Lining of the gastrointestinal tract
Lungs
Liver, pancreas, stomach, intestines, oesophagus
What do mesoderm cells become?
Muscles
Skin
Bones
Heart, kidneys, bladder, testies
What do ectoderm cells become?
Outer layer of skin
Sweat glands
Hair
Nervous system
What is the name of a zygote that has divided into 16 cells?
Morula
What is the name given to the process of the zygote mitotically dividing?
Cleavage
What is the name of a fertilised egg cell?
Zygote
What happens after cleavage to for a blastocyst?
Compaction
What is the name of the glycoprotein membrane surrounding the morula?
Zona pellucida
What is the cavity in a blastocyst called?
Blastocyst cavity
What does cleavage first produce?
2 blastomeres
What is the potency of the cells in a morula?
Totipotent - can become any type of cell
What is pre-implantation genetic diagnosis?
Used in assisted reproductive technique
Removal of cell from morula
Tested for heritable conditions
Prior to transfer into mother
What is the stage after cleavage and the formation of the morula?
Compaction
What is the name of the cell after compaction?
Blastocyst
What are the inner and outer cell masses of a blastocyst called?
Inner - embryoblast
Outer - trophoblast
What is the potency of cells after compaction?
Pluripotent - can become many cells
What are the next stages after compaction?
Hatching and implantation
What do the trophoblasts differentiate into?
Syncytiotrophoblasts
Cytotrophoblasts
What do the embryoblsats differentiate into?
Epiblasts
Hypoblasts
(The bilaminer disk)
What week do the epiblasts and trophoblasts differentiate?
Week 2
What is the top layer of the epiblast?
Epiblast
What is the small cavity within the bilaminer disk?
Which layer?
Amniotic cavity
Epiblast
What is the name given to the fused vacuoles in the uterine?
Lacunae
What is the name of the larger cavity?
Primitive yolk sac
Where is the primitive yolk sac positioned?
Between the hypoblasts and cytotrophoblasts
What has to happen for uteroplacental circulation to begin?
Lacuna becomes continuous with the sinusoids (maternal capillaries)
What forms the secondary yolk sac?
Primitive yolk sac pinches off
What forms the chorionic cavity?
Extraembryonic mesoderm merge
What is the embryo suspended by?
What will it eventually become?
Connecting stalk
Umbilical cord
What is the streak in the bilaminer disk call?
Primitive streak
What does the bilaminer disk become?
What is it made from?
Trilaminer disk
Ectoderm
Mesoderm
Endoderm
(Germ layers)
What do the mesoderm cells differentiate into?
Notochord cells
What forms the neural tube?
The ectoderm folding inwards
What is an ectopic pregnancy?
Implantation anywhere other than the uterine body - commonly the Fallopian tubes
What is placenta praevia?
Implantation in the lower uterine segment
Placenta blocks the cervix
Can cause haemorrhage due to the vulnerable blood vessels of the placenta
When are 50% zygotes lost?
First 2-3 weeks
What comes first neurulation or gastrulation?
Gastrulation
When does gastrulation happen?
Third week
What does the dermatome become?
Dermis - the skin
What does the myotome become?
Muscles
What does the sclerotome become?
Bones
When does cleavage take place?
Week 1
When does implantation take place?
Week 1
When does hatching take place?
Week 1
When does the bilaminer disk form?
Week 2
What happens on day 9?
The yolk sac forms
What happens on day 14?
Chorionic cavity is formed
When does the secondary yolk sac form?
Day 13
What happens on day 12?
Uteroplacental circulation begins
What does the notochord become?
The vertebral column - spinal chord
What do somites become?
Vertebral column, ribs and extensor muscles of spine
What do the somatic layers become?
Diaphragm and limb muscles
What forms the muscles of the heart?
Splanchnic layer
What is a splanchnic mesoderm?
Overlies the endoderm and is a layer continuous with mesoderm covering the yolk sac
What is the somatic mesoderm?
The outer layer formed after the split of the lateral plate mesoderm
