embryology 1 and 2 Flashcards
what gamete has 22+X and 2 polar bodies?
ovum
what organelle is inherited from the mother and what is the importance of this?
Mitochondria and cell organelles inherited from mum; this is important because the mitochondria have its own DNA so will be affected if the mother is as the dad cannot pass on organelles, so ALL children are affected
how many cells are in a morula?
16 cells
what is the stage after morula formation called?
blastocyst. it is formed as cell number increases so diffusion is made harder as it cannot reach the cells in the centre as easy compared to a morula
how long does the pre embryonic phase last?
0 - 3 weeks
how long does the embryonic phase last
4 - 8 weeks
what is the consequence of the cilia being damaged?
the zygote can no longer be pushed along the fallopian tubes and can lead it to being embedded at one point and, if it keeps developing, it can lead to an ectopic pregnancy which can cause rupture
what is implantation and when does it occur?
when the blastocyst becomes implanted in the endometrial lining (week 2)
what does the trophoblast develop into eventually?
chorion. this also develops finger-like projections called chorionic villi
describe 3 functions of the chorion
implantation
forms part of the placenta in due course
secretes Human Chorionic Gonadotropin (HCG) which is used to detect pregnancy (secreted in urine)
what is the function of HCG?
it is released by the chorion to signal ovary to produce more progesterone and oestrogen
what week does the chorion develop into the placenta and what happens to HCG levels?
12 -15 weeks, levels decrease as no longer required, thus decreasing progesterone and oestrogen
what causes morning sickness@
HCG in high amounts in maternal blood stream but then this ends at the end of the first semester when the placenta is formed
what is the myometrium
the muscular layer behind the endometrium
