BL12 - Embryology Flashcards
Name the unspecialised cell that creates sperm?
Spermatogonium
Explain the differentiation process of sperm cells
Spermatogonium -MITOSIS- Primary spermatocytes - MEIOSIS 1- secondary spermacytes -MEIOSIS 2- spermatids
Explain the differentiation process of egg cells
oogonium - primary oocyte - secondary oocyte - ovum + 3 polar bodies
Name the unspecialised cell that creates sperm?
oogonium
In females when does meiosis one occur for primary oocytes?
Puberty
In females when does meiosis 2 occur for secondary oocytes?
Apon the entry of the sperm
Where are the ova formed?
Ovaries
What part of the female reproductive organ are the released into?
Ampulla of the fallopian tube
What is the cervix
Tight circular muscle that sits between the vagina and the uterus
How long do sperm live for?
5 days
How long do secondary oocytes live for?
12-24hrs
What are the two layers a sperm must get through to get to the egg?
Corona Radiata
Zona Pelucida
What is the embryonic age?
Time since fertiliasation
What is the gestational age?
Time since last period
What is the embryonic period?
3-8 weeks
What is the foetal period?
9-38 weeks
In IVF what stage is the zygote at when it is implanted?
Blastocyst
What is the process called when the zona pellucida is lost?
Hatching
Fertilisation =
Day 4
Day 5
Zygote
Morula
Blastocyst (inner and outcell mass)
What does trophoblast mean?
FOOD BUD
Outer cell mass in a blastocyst
Where is a normal implantation?
Superior and posterior
What day is implantation day?
6th Day
What is an ectopic pregnancy?
When the blastocyst doesn’t implant in the uterus
What is placenta previa?
Implantation occurs at the bottom of the uterus so the birthing canal will be blocked. Can cause haemorrhage on birth so caesarean sections used
What occurs in week 2 to the Inner mass cell ?
Inner mass cell divide into Epiblast
Hypoblast
What occurs in week 2 to the Trophoblast?
Divides and forms Cytotrophoblast synctiotropoblasts
What cavities forms in week 2? and where do they come from?
Hypoblast forms
Yolk sack
Chorionic cavity
What does the Yolk sack form from?
Hypoblast
What does the epiblast form?
Amniotic cavity
What is gastrulation?
Establishment of 3 germ layers
Name the key events of embryology. 6
1) Fertilisation Wk1
2) Implantation Wk2
3) Gastrulation Wk3
4) Neurulation
5) Segmentation
6) Folding
What feature appears on the epiblast of at the end of the second week?
Primitive streak and primitive node
How does a bilayer become a trilayer?
Epiblast and Hypoblast
Hypoblast is displaced by new cells that form the mesoderm
What does the ectoderm form?
Epidermis and Neural Crest (later NS)
What does the mesoderm form?
and then give 4 examples
Somites
muscle; the cartilage of the ribs and vertebrae; the dermis, the notochord, blood and blood vessels, bone, and connective tissue.
What does the endoderm form?
endoderm gives rise to the epithelium of the digestive system and respiratory system, and organs associated with the digestive system, such as the liver and pancreas
What to the two gaps in the mesosome form?
Mouth and Anus
What is Situs inversus?
Condition where organs are reversed
When does the new human become bilaterally symmetrical?
End of week 2.
Prior to gastrulation
What is the notochord formed from?
Mesoderm
What is the notochords role in Neuralation?
signalling role
Notochord directs conversion of overlying ectoderm to
NEURECTODERM
What happens to the mesoderm in neurulation?
splanchnic mesoderm
somatic mesoderm
intraembryonic
coelom
Organisation of paraxial mesoderm into segments
What is neurulation?
Folding of the neural plate into neural tube
What is a somite?
Somites block of mesoderm cells arranged around a small cavity
What two things happen is segmentation?
gives rise to repeating structures (ribs, vertebrae, spinal cord segments)
Guides innervation
How many somites?
31
Into which tissue does the blastocyst implant normally?
Uterine lining
At which developmental stage does implantation normally occur?
Blastocyst
From which embryonic tissue are the three germ layers (and consequently all of the tissues of the body) derived?
Epiblast
Initial development of which system of the body is
driven directly by the notochord?
Central nervous system
Which tissue lines the intraembryonic coelom (body cavity)?
Mesoderm
The notochord forms the nucleus pulposus of
intervertebral disk.. T/F?
True
Which part of the mother immune system is dampened during pregnancy?
Cell mediated Response
