Embryology part 1 Flashcards
What are male gametes called?
Sperm
Where are male gametes produced ?
testis
What cell does sperm develop from ?
A spermatogonium
What are female gametes called?
Eggs or ovum
Where are female gametes produced?
In the ovaries
What cell does eggs develop from ?
Oogonium
What is the process of producing gametes called?
Meiosis
What does one cycle of meiosis in males give rise to ?
4 sperm
What does one cycle of meiosis in females give rise to ?
1 egg and 3 polar bodies which are then destroyed
What is fertilisation ?
When the pronucleus of the egg and sperm combine
What is the diploid cell produced in fertilisation called?
a zygote
Where is mitochondria genetic information from ?
The mother
What happen to the zygote after fertilisation ?
It undergoes mitosis and forms a solid ball of cells.
What is this solid ball of cells called?
A morula
What happens to a morula ?
It then divides and forms a blastocyst
Why does a blastocyst form ?
Diffusion is not sufficient to get things from the outside
What then happens to the blastocyst ?
It splits into two. This forms the trophoblast (outer layer) and the inner mass of cells.
A cavity forms in the centre and nutrient can get to the tissue faster.
Why does the placenta need to from ?
it is a better method of getting nutrients into all the cells
When does the baby become dependant on the placenta?
At week 12
Where does fertilisation take place ?
In the fallopian tube
Where is the morula ?
Moving down the fallopian tube
Where is the blastocyte ?
In the uterus
How does the zygote and morula move down the fallopian tube ?
Cillia.
What happens if the cillia in the fallopian tube is not working ?
Ectopic pregnancy
How many days dose it take to travel down the fallopian tube ?
6-7 days
When is ovulation in relation to a period ?
14 days before the period starts
What is implantation ?
The process where the blastocyte buries itself into the endometrial lining.
What part of the blastocyte controlled implantation ?
The trophoblast
What does the trophoblast divide to from ?
Two layers creating the chorion
Why is the chorion important in implantation ?
It develops chorionic villi which burry into the endometrium lining,
How do pregnancy tests work ?
They detect HCG which is released by the chorion
What is HCG ?
A hormone used to prevent the sheading of the endometrial lining.
What is the endothelial lining called once’s it has been implanted in ?
The decidua basalis
Describe what happens to the inner cell mass ?
Flattens and forms two layered disc.
What are the two layers of the inner cell mass disc called?
The epiblast and the hypoblast
What are the two cavities created by the inner cell mass disc called?
Amniotic cavity and the yolk sac
What are fraternal twins ?
Non-identical twins created when two ova are released and both fertilised.
What structures does the trophoblast continue to develop and create ?
The umbilical cord, foetal blood vessels, placenta
What happens to the bilaminar disc?
- Primitive streak forms creates an axis
- Gastrulation
(Epiblast cells migrate to lie between the epiblast and the hypoblast layers - These cell displace the hypoblast and form a trilaminar
- The ectoderm, the mesoderm and the endoderm)
What happens after gastrulation ?
The ectoderm starts to descend down and forms a ball of cells which become disconnected from the ectoderm this is called the notochord.
What is neurulation ?
Now the ectodermal cells in the primitive streak will thicken and form a neural plate which will drip down forming a valley will two hills on either side. The two hills join and the neural tube is disconnected from the ectoderm. This will happen along the whole length if the primitive streak. The top develops to form the brain and the rest the spinal cord. The formation of the neural tube is called neurulation. To some extent this can been seen in our spinal cord.
What happens to the mesoderm after neurulation ?
Mesoderm thickens and then separates into three parts.
The paraxial mesoderm, the intermediate plate mesoderm and the lateral plate mesoderm
What happens to the paraxial mesoderm after it is formed ?
Divides into the dermatome, myotome and sclerotome.
The dermatome will migrate and form the dermis of the skin. the myotome will migrate and form the muscles and the sclerotome will migrate and form the bones including the vertebrae.
When they migrate they take there innervation with them. So if something if from the T10 dermatome it means that it migrated form the T10 spinal cord level.
