WEEK 1 - Fertilization Creates Babies Immediately = FCBI --> F-fertilization, C-cleavage, B-blastocyst, I-implantation.
• F-fertilization: Occur in the ampulla of the fallopian tube. Sperm binds the ZP (zona pellucida) of the secondary oocyte -->acrosome reaction (enzymes breakdown ZP) --> sperm penetrate ZP --> cortical reaction (renders ZP impermeable to other sperm) --> sperm and secondary oocyte membrane fuse --> sperm male genetic material (MALE PRONUCLEUS) enters the secondary oocyte’s cytoplasm --> Male and female pronuclei fuse to form a zygote.
• C-clevage: Serial mitotic division of the zygote to form a blastocyst consisting of increasingly smaller blastomeres (the individual embryonic cells at this stage). At the 32-cell stage, blastomeres form a morula.
• Blastocyst formation (occur when fluid secreted within the morula): The blastocyst consists of a spherical layer of around 128 cells surrounding a central fluid-filled cavity called the blastocoel. It contains an ICM (inner cell mass) and an OCM (outer cell mass)
o ICM = Embryoblast --> embryo and fetus
o OCM = Trophoblast --> placenta.