Fertilisation Flashcards
How long can sperm survive?
How long can egg survive?
Sperm- 4-6 days
Egg- 1-2 days
How is egg transported?
From ovary carried out in antral fluid
Smooth muscle and fimbriae move egg to fallopian tube
Cilia carry egg to uterus
What carries egg to fallopian tube?
Smooth muscle and fimbrinae
Why do sperm need oestrogen?
Source of glucose
Is vagina acidic or alkali?
Acidic
Define capacitation?
Maturation process- tail stronger
Plasma membrane develops- allow fusion with egg
Where does fertilisation occur?
Ampulla of fallopian tube
How do sperm and ova join?
Glycoproteins on zona pellucida- receptors (ZP3)
Sperm head- binding proteins
What receptors are used during fertilisations?
Glycoproteins on zona pellucida- receptors (ZP3)
What occurs do zona pellucida once binding has occured?
Acrosome reaction
Enzyme cause zona pellucida digested
What is formed when fusion occurs?
Zygote
How are other sperm cells prevented from entering?
After fertilisation- reaction
Hardening of zona pellucida by enzymes inactivate ZP3
When is meiosis 2 completed?
After fertilisation
Outline what occurs on day 1?
Fusion of sperm and egg in ampulla of fallopian tube
2) Glycoproteins on zona pellucida are receptors (ZP3) and sperm head contains binding proteins
3) Binding = acrosome reaction– zona pellucida causing it to be digested
4) Fusion can now occur with the plasma membrane
5) Zygote formed- head of sperm passes into cytosol and fertilisation occurs
6) Fertilisation causes a reaction- prevents entry of other sperm - exocytosis of vesicles contain enzymes (inactivate ZP3)- harden zona pellucida
7) Meiosis II is completed- 2nd polar body degenerates
8) 2 sets of haploid chromosomes are present- 23 sperm and 23 egg = pronuclei
9) Migrate to centre of the cell- haploid chromosomes fuse
10) DNA replication occurs in preparation for meiotic division
11) Mitosis then occurs
What occurs during cleavage process 2/3?
Progesterone relaxes smooth muscle
Zygote pass through fallopian tube
Cleavage increase number cells present
Cells totipotent
What hormone allows zygote move through fallopian tube?
Progesterone- relax smooth muscle
Define totipotent?
Develop into entire individual
State diff processes after fertilisation?
Brief outline
Fertilisation- day 1
Cleavage- day 2/3- zygote move down fallop
Compaction- day 4- cell flatten, tight junctions
Cavitation and differentation- day 5- formation blastocysts
Expansion- day 5/6- cavity expand, zp thins
Hatching- day 6+- embryo out zp, imp for implanting
What occurs during compaction day 4?
Cells flatten
Tight junctions form
Polarisation outer cells
Allow rapid differentiation
What occurs cavitation and differentiation day 5?
Blastocysts formed- fluid filled cavity expands
Lose totipotency
What occurs in expansion day 5/6?
Cavity expands
Zona pellucida thins
What occurs in hatching day 6?
Blastocyst expands
Embryo out zona pellucida
Essential implantation
What process is essential for implantation?
Hatching
When does embryo move from zona pellucida?
During hatching 6
Outline how many cells?
1) Fertilisation
2) 2 cell stage- day 1
3) 4 cell stage- day 2
4) 8 cell uncompacted morula- day 3/4
5) 8 cell compacted morula- day 4
6) Early blastocyst- day 5
7) Late stage blastocyst (hatching)- day 6/7
8) Implantation blastocyst- day 8/9
What days does implantation of blastocyst occur?
Day 8/9
When is morula formed?
Day 4
How many cells is morula?
16
How many c
