Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
35 Cards in this Set
- Front
- Back
|
What does folic acid prevent in pregnancy?
|
spinal tube defects/spina bifida
|
|
|
What are the four key processes in development?
|
growth, morphogenesis, differentiation, induction
|
|
|
What is teratology? What do teratogens do? give an example?
|
'study of monsters'. Cause birth defects. Thalidamide - severe birth defects, ionising radiation, cigarette smoke.
|
|
|
What is the embryonic period?
|
the first 8 weeks of human life
|
|
|
What are the 5 key events of the embryonic period?
|
Conception. Body axes established. Organ primordia in place. 3 germ layers form. Early placenta has developed.
|
|
|
What occurs in the first week of life and where does this take place?
|
fertilisation, cleavage, blastocyst formation, implantation. In the oviduct.
|
|
|
Where does fertilisation occur?
|
Ampulla - widest part of the oviduct.
|
|
|
What are the zygotic cells called after cleavage?
|
Blastomeres.
|
|
|
What does gametogenesis create?
|
haploid cells: ovum/sperm
|
|
|
what kind of cell division occurs during cleavage?
|
mitosis
|
|
|
How common are fraternal twins in the UK?
|
13/1000 births
|
|
|
What is the heavy protein coat surrounding the egg called?
|
zona pellucida
|
|
|
What is a morula?
|
a fertilised egg that has undergone cleavage to become a 16-cell ball
|
|
|
What happens on day 4/5 to the morula?
|
Begins to hollow out forming a fluid-filled cavity and the outer layer cells differentiate to become the trophoblast
|
|
|
What is the fate of trophoblast cells?
|
destined to become the placenta
|
|
|
What is the inner cell mass of the blastocyst on day 4/5 called and what will this become?
|
embryoblast, designated to become the embryo proper. Retains pluripotency.
|
|
|
What twins form at day 4/5?
|
monozygotic twins
|
|
|
When does implantation occur?
|
day 6-7
|
|
|
What occurs before implantation can happen?
|
hatching - blastocyst hatches out of zona pellucida. trophoblast differentiates into the syncytiotrophoblast (outer cells) and the cytotrophoblast (inner cells)
|
|
|
What is the difference between the syncytio- and the cyto- trophoblast?
|
syncytio is a multinuclear cell mass and cyto has distinct cells
|
|
|
What stage and day of pregnancy is the most likely stage of failure?
|
Implantation - day 7
|
|
|
What occurs in the 'week of 2s'? (second week of pregnancy)
|
2 layered embryo, 2 cavities (amniotic and yolk sac), 2 spaces (extraembryonic mesoderm - splanchnic, somatopleural)
|
|
|
What forms over the site where the blastocyst burrows into the uterus wall?
|
fibrin plug
|
|
|
When and how do the epiblast and hypoblast form?
|
day 8/9, when the cells of the embryoblast begin to differentiate
|
|
|
what formation are the epi and hypo blast originally in?
|
bilaminar disc
|
|
|
where is the hypoblast and what does it do?
|
layer adjacent to the blastocoel cavity. secretes a membrane around the blastocoel which is the primitive yolk sac.
|
|
|
where is the epiblast and what does it do?
|
above the hypoblast. grows and splits to form the fluid-filled amniotic cavity.
|
|
|
What occurs at day 10/12
|
new loose connective tissue (extraembryonic mesoderm) appears between the cytotrophoblast and the yolk sac. Syncytotrophoblast fingers contact materal blood circulation.
|
|
|
What does the extraembryonic mesoderm do?
|
ultimately splits to form the chorionic/extra-embryonic cavity
|
|
|
What hormone does the trophoblast tissue secrete at day 13/14?
|
human chorionic gonadotrophin (HCG)
|
|
|
Why might a woman think she is not pregnant at days 13/14 of a pregnancy?
|
implantation bleed
|
|
|
What do trophoblast tissues form as implantation proceeds?
|
villi
|
|
|
what does the chorionic cavity do at day 13/14?
|
surrounds the whole thing, forming the secondary yolk sac, and the primary yolk sac shrinks.
|
|
|
what is the embryonic disc supported by?
|
the connecting stalk which is destined to become the umbilical cord.
|
|
|
what 4 things have occured by 2 weeks?
|
diploid individual. two distinct cell layers (epiblast/hypoblast), implanted into uterus, connected to maternal circulation
|
