Embryology Flashcards
What is the path of the sperm cell?
-corona radiata
-zona pellucida
-plasma membrane of secondary oocyte
-cytoplasm of secondary oocyte
Explain the stages of formation of the morula and blastocyst
Day 1- cleavage of zygote, two cell stage
Day 2- cleavage of zygote, four cell stage
Day 4- morula
Day 5- blastocyst
What events take place within the first week of development
- fertilisation= occurs within uterine tube after ovulation
- cleavage= first completed 30 hours after fertilisation
- morula= 3-4 days after fertilisation
- blastocyst= 4.5-5 days after fertilisation
- Implantation= 6 days after fertilisation
What are the two layers that make up the uterus?
endometrium and myometrium
What is neuralation
Neural plate starts to develop at days 18-23
What is angiogenesis 1?
-individual blood cells appear, join together to form tubes
-heart starts to develop
-heart starts beating around day 23
Day 22
What is angiogenesis 2?
-rudimentary blood system
-folded heart single chamber
Day 26
What is identifiable of an embryo at week 8?
-foetus recognisable as an infant
-internal organs developed as structures
-limbs developed
-genitalia starting to develop
What does the foetal phase consist of?
-from 9 weeks to full term
-characterised by growth, development of structures and development of functionality
What is the main difference between the 2nd and third trimester in terms of development?
2nd trimester mainly grow in length
3rd trimester mainly grow in weight
What is the difference between identical and non identical twins?
identical twins:
-share genes
-same gender
-monozygotic
-1 placenta
nonidentical twins:
-50% of genes are the same
-dizygotic
-2 placentas
What happens during fertilisation to produce a single diploid nucleus?
the genetic material from a haploid sperm cell and a haploid secondary oocyte merges to form the single diploid nucleus
How is a zygote produced?
penetration of the zona pellucid is facilitated by enzymes in the sperms acrosome, forming a zygote
What is a blastocyst?
-the morula (solid sphere of cells) develops into a blastocyst which is a hollow ball of cells differentiated into a trophoblast and an inner cell mass
What is implantation?
the attachment of a blastocyst to the endometrium
What does the hypoblast form and do?
-forms the yolk sac
-this transfers nutrients to the embryo, forms blood cells, produces primordial germ cells and forms part of the gut
What are the 3 primary germ layers and what do they do?
-ectoderm, mesoderm, endoderm
-these from all tissue and organs of the developing organism
What is the role of the chorionic villi?
-projections of the chorion
-connect to the embryonic heart so that maternal and fatal blood vessels are brought into close proximity so nutrients and wastes are exchanged between maternal and fetal blood
What is the placenta and what are its functions?
-site of exchange of nutrients and wastes between the mother and foetus
-protective barrier, stores nutrients and produces several hormones to maintain pregnancy
How is the umbilical cord different from the placenta?
it is the actual connection between the placenta and embryo
