Embryology 1.3 Flashcards
What is implantation? (week 2 )
blastocyst burrows itself into the endometrial layer and stays there for 39 weeks after
Why is the blastocyst able to burrow into endometrial layer?
because of outer cell mass- trophoblast
What’s going to happen to the trophoblast ( the outer cell mass) ?
outer cell mass (initially a single layer) is going to divide and form two layers.
Cellular changes within cells until it becomes a chorion.
What is the chorion going to develop?
finger like processes called chorionic villi.
What are the functions of chorionic villi?
- Implantation process
- Forms part of the placenta in due course
- Secretes human Chorionic gonadotropin (HCG) (used to detect pregnancy)
Describe why the endometrium sheds?
Oestrogen and progesterone has a function of acting on this endometrium of the uterus and making it develop.
The endometrium keeps developing as long as the ovary keeps secreting this hormone. Hormones secreted for about 3 weeks and then ceased to be secreted.
What hormone does the chorion secrete to keep implanted embryo in endometrium?
Human Chorionic Gonadotropin
What does HCG encourage?
ovaries to keep producing oestrogen and progesterone
What has happened to the chorion at around weeks 12-15?
chorion developed into the placenta (has own system of blood vessels) and is now able to nourish the growing embryo
What are the side effects of HCG?
morning sickness
When does morning sickness disappear?
end of the first trimester
How do we detect pregnancy?
HCG in the urine
What is the decidua?
the endometrium after implantation has occurred
Recap of terminology?
zygote- first cell in the body that’s formed
morula- when zygote is divided and it forms that solid mass of cells
blastocyst- structure with cavity, outer and inner cell layer
trophoblast
chorion
What happens to the inner cell mass during second week?
inner cell mass going to flatten itself and form two layers.
The two layered flat disc is called the bilaminar disc
