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Flashcards in implantation and development Deck (59)
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what happens on day 1 after fertilisation?

first cleavage


what happens on day 2 after fertilisation?

2 cell stage


what happens on days 3-4?

4 cell stage to an 8 cell uncompacted morula


what happens on day 4

8 cell compacted morula


what happens on day 5?

early blastocyst - (trophectroderm, blastocoel, inner cell mass)


what happens on day 6-7?

late stage blastocyst (hatching)


what happens day 8-9?

implantation of the blastocyst


what is transfer of the conceptus through the oviduct facilitated by?

changing endocrine milieu of the early luteal phase with its rising ratio of progesterone to oestrogen, which effects the oviducal and uterine musculature and relaxes the isthmus sphincter.


does the size of the conceptus change as blastomeres are undergoing devisions?

no the total size of the conceptus stays the same.
as a consequence the size of individual blastomeres is reduced progressively.


what happens when the conceptus reaches the maternal endometrium?

attachment and implantation


what is in the structure of a human blastocyst

zona pellucida
blastoceal cavity
inner cell mass


when is pregnancy initiated?

when the conceptus has signalled its presence successfully to the mother.


in the first 14-16 days of human development what are the two cell types types and what do they give rise to?

pluripotent embryonic cells - will give rise to a fetus
they are set apart and enveloped within various extra embryonic cells that will give rise to the supporting structures (mainly the placenta)


when and what is the embryogenic phase of development?

up to day 14
it is the generation of an embryo.


how long does the embryonic phase last for?

6 weeks


what happens during the embryonic phase?

various embryonic cells and tissue types differentiate and the basic body plan is laid down such that eventually tiny foetus formed.


what marks the end of the first trimester?

the transition from embryo to foetus


what are the essential factors for embryo implantation?

the implantation window (receptive endometrium)
healthy embryo at the blastocyst stage
communication between mother and the baby at the time of implantation.


what are the features of a receptive endometrium?

shortening of microvilli
loss of surface negative charge
thinning of the mucin coat
formation of pinopodes


what are the features of a non receptive endometrium

long apical microvilli
high surface negative charge
thick mucin layer


what is decidualization?

post ovulatory process of endometrial remodelling in preparation for pregnancy, which includes secretory transformation of the uterine glands, influx of specialised uterine natural killer cells and vascular remodelling.


what do decidualizing stromal cells acquire the ability to do?

- regulate trophoblast invasion
- resist inflammatory and oxidative insults
- dampen maternal immune responses


in humans when does decidualization of stromal cells occur?

mid luteal phase of the menstrual cycle
independently of pregnancy


what hormone drives decidualization?

it drives changes at both transcriptome and proteomic level


when does compaction of the conceptus occur?

around the 8 to 16 cell stage


what does the process of compaction involve?

maximising intercellular contacts and also the transformation of the cell phenotype from radially symmetrical to highly polarised or epithelioid.


what two cell types does the blastocyst contain?

trophoblast cells
inner mast cells


what is the first extra-embronic tissue made up of?

trophoblast cells
the do not contribute to the embryo of foetus


what is the chorion and what is it derived from?

it is an accessory foetal membrane which is concerned with the nutrition and support of the embryo and foetus
it is derived from trophoblast cells


what are the two function of the zona pellucida?

- prevents the blastomeres of the conceptus form falling apart during earl cleavage, before compaction.
- prevents two genetically distinct conceptus from sticking together to make a single chimeric conceptus composed of two sets of cells each of distinct genotype.