Timeline of Fertilisation Flashcards
What is the first stage?
Gametogenesis
What does gametogenesis involve?
The formation of sex cells involving mitosis and meiosis
What are the sex cells?
Spermatozoa and ovum
What does fertilisation involve?
The fusion of the male and female gametes to form a zygote
What change must the sperm undergo before fertilisation?
Capacitation of sperm
What does capacitation involve?
Secretions within the female reproductive system capacitate the sperm, getting it ready for fertilisation by changing the chemical structure of the head of the sperm.
Where does fertilisation usually take place?
Ampulla - widest part of uterine tube
What must sperm cells pass through in order to fertilise egg?
- Corona radiate
2. Zona pellucida
What is the corona radiate?
Cells round outside of oocyte
What is the zona pellucida?
Outer jacket of oocyte
How does the sperm penetrate the zona pellucida?
Acrosome reaction - The acrosome (in head of sperm) releases degrative enzymes that break down the zona pellucida. This allows sperm to penetrate and the head of sperm (containing genetic information) makes its way into oocyte.
What is purpose of cortical reaction? When does it occur?
Occurs after sperm penetration (after zygote forms). This make the zona pellucida impenetrable, preventing another sperm from fertilising the egg.
After this fertilisation, what occurs?
Cleavage - zygote cells divide rapidly
What changes in size does the zygote undergo?
No change in size despite rapid division - blastomeres get smaller, zona pellucida keeps it same size
After cleavage, what structure forms?
Morula
