Fertilisation Flashcards
Fertilisation
Fusion of male and female gamete in the fallopian tubes
What surrounds the egg
Layer of cells called the corona radiata and a protein layer (non-cellular) called the zona pellucida
How can sperms penetrate the egg
Sperm head contains enzymes in the acrosome which allows sperm working together to penetrate the egg
Cortical reaction
Once it has been penetrated a membrane forms around the egg to prevent the entrance of other sperm which could then make the egg not viable
Zygote
single cell formed at fertilisation in the fallopian tube which undergoes cleavage and becomes identical cells
Cleavage
series of rapid mitotic divisions characterised by the absence of growth of daughter cells, continues until the blastocyst stage, as number of cell increases their size decreases as they all share the same cytoplasm
What do the cilia do
Line the fallopian tube and beat towards the uterus directing the developing zygote as cleavage is still occurring
Morula
ball of identical cells in the fallopian tube, takes 4-5 days to form, called a morula after the 8 cell stage, cells in the morula continue undergoing mitosis becoming a hollow with a mass of genetically identical cells at one end
Blastocyst
hollow ball of cells that surround a cavity filled with fluid, contain identical undifferentiated cells, formed 7 days after fertilisation
What is the blastocyst made up of
Inner cell mass, trophoblast and blastocoele
Inner cell mass
mass of around 30 cells at one side of the blastocyst that develop into the embryo (embryonic stem cells)
Trophoblast
Cells that become the membrane
Blastocoele
Fluid-filled section
Implantation
when the blastocysts burrows into the thickened endometrium
Basic timeline
Fertilisation —-> zygote, cleavage (mitosis), blastocyst (day 5-7)- inner cell mass and outer sphere, implantation (day 7-10)
