Intoduction Flashcards
Define morphogenesis
Development of form and structure
Define diiferentitation
Specialisation for function
What happens in fertilisation? And what is the mass called at this stage?
Oocyte is released from ovary Travels along Fallopian tube Fertilised by sperm in the ampulla Now called a zygote Ideal implantation site is posterior uterine wall
Describe cleavage
The first mitotic division
Results in 2 blastomeres of equal size
When is the zygote Called a morella?
All cells are identical in size and genetic.
All cells are to totipotent (embryonic stem cells)
What is pre-implantation genetic diagnosis
When a single cell is safely remove from the IVF morella and tested for serious heritable disease, prior to transfer and implantation of morella to mother’s womb.
What is compaction?
When the first cavity is formed.
Now called a blastocyst (primitive fluid filled)
Inner cell mass will from embryo- embryoblast
Outer cell will form placenta and membranes- trophoblast
Cells now pluripotent
What happens in week 2
Differentiation- distinct cell layers emerge from outer cell mass= the syncytiotrophoblast (multicellular sheet at utter layer ) and the cytotrophoblast (1 cell inner layer )
The inner cell mass becomes the biluminar disk=
Epiblast (forms embryo) and hypoblast (will become yolk)
Describe all the parts present in the end of the 2nd week.
Conceptus has implanted (can access maternal support)
Embryo and 2 cavities (amniotic cavity at top and yolk sac at bottom)
Suspended by a connecting stalk
And supported by the chorionic cavity (protective sac)
See diagram in lecture in body logistics
Describe implantation
The uterine epithelium is breached and cenceptus implants within uterine stroma.
Establishes maternal blood flow in placenta
Establishes basic structural unit of exchange - the chorionic villus.
List some conditions related to implantation defects.
IUGR
Pre-eclampsia
Ectopic pregnancy
Placenta praevia
What is an ectopic pregnancy?
Implantation at site other than uterine body (commonly Fallopian tube)
Can be peritoneal or ovarian
Life threatening very quickly- even before pregnancy is known
What is a placenta praevia?
Implantation n the lower uterine segment
Can cause haemorrhage in pregnancy
Requires c-section otherwise baby tries to push through placenta
Why is ectopic pregnancy dangerous?
Baby doesn’t have room to grow so can cause rupturing of tubes resulting in large bloodless into abdomen
Why does a placenta praevia need a c-section?
As spontaneous labour causes the baby to push too the placenta causing large blood loss
