Fertilisation and early embryo Flashcards
Where does fertilisation occur inside the female?
In the ampulla - a wider part of the oviduct near the ovary
What is capacitation?
Spermatozoa undergo changes within the female tract that allow them to become fertile
What changes occur to the spermatozoa during capacitation?
- The surface molecules in epididymal sperm become coated with seminal plasma proteins that mask membrane molecules.
- In the female tract the seminal plasma coating and some surface molecules are removed
- hyperactive motility pattern
Where in the female tract are sperm stored until ovulation?
Isthmus of the oviduct - narrow part
What are the 3 stages that the sperm must complete for successful fertilisation?
- Bind to the zona pellucida
- Undergo the acrosome reaction
- Penetrate the zona pellucida and fuse with the oocyte membrane
What is the acrosomal reaction?
Sperm release enzymes from the head to digest the zona pellucida
What causes the zona block?
- Oocyte and sperm membranes fuse
- oocyte releases cortical granules
- stops further sperm penetrating
When does the 2nd meiotic division occur?
After fertilisation
What is syngamy?
Male and female pronuclei fuse to form a gamete
What name is given to the rapid mitotic division of the zygote?
Cleavage
What is formed from cleavage?
The morula
What is formed from gastrulation?
Blastocyst
What is the purpose of maternal recognition of pregnancy?
Block the luteolytic signal which prevents pregnancy loss. maintains the corpus luteum so that progesterone is still produced before the placenta develops.
