Fertilization

• What is fertilization?


  Union of male and female gametes

  
• What does oocyte activation conclude with?

  Congregation of paternal and maternal chromosomes
• What is sperm capacitation?

  Changes in sperm to prepare for fertilization

  
• What is the role of the acrosome reaction?

  Essential for sperm-egg plasma membrane fusion

  
• What does oocyte activation include?

  Completion of maternal meiosis and EGA
• How is sperm capacitation partly mediated?

  By the female reproductive tract
• What changes occur to sperm during capacitation?

  Decrease in surface net negative charge

  
• What are some changes to sperm during capacitation?

  Modification of surface components and membrane permeability

  
• What is the acrosome reaction (AR)?

  Ca$^{2+}$-dependent exocytosis event
• What was the old model for the acrosome reaction trigger?

  Triggered by sperm binding to the zona pellucida

  
• What is the cumulus oophorous?

  Cloud of cumulus cells surrounding the oocyte

  
• When does the acrosome reaction occur?

  Before zona pellucida contact

  
• What does the acrosome reaction liberate?

  Hydrolytic enzymes from the acrosome
• What is the role of acrosin in fertilization?

  It is a serine protease that aids penetration

  
• What is the sperm-oolemma interaction?

  Sperm can bind to the egg plasma membrane

  
• What mediates sperm binding to the oolemma?

  Sperm IgG-like acrosomal protein, Izumo

  
• What is the principal Izumo receptor on eggs?

  Juno

  
• What happens to Juno after fertilization?

  It is rapidly depleted from the egg

  
• What is polyspermy?

  Fertilization by more than one sperm
• How is polyspermy blocked?

  Through zona block and plasma membrane block

  
• What does cortical granule exocytosis release?

  Protease, ovastacin into perivitelline space
• What happens to ZP2 after ovastacin cleaves it?

  It is inactivated and no longer binds sperm
• What is the role of Juno in polyspermy block?

  It acts as a decoy for sperm binding
• What occurs during ICSI?

  Sperm injection into oocyte causes fertilization events

  
• What percentage of human assisted reproduction cycles are ICSI?

  65%
• What is still unknown about ICSI?

  How it causes fertilization events
• What initiates oocyte activation?

  Sperm capacitation
• What is the role of capacitation in sperm function?

  It drives hyperactivated sperm motility
• Where does capacitation occur in the female reproductive system?

  In the female reproductive tract
• What is the acrosome reaction?

  It allows sperm to bind to zona pellucida
• What is required for sperm to undergo capacitation?

  The right environment in the female tract
• What does PTM stand for?

  Post transcriptional modification
• What changes occur during sperm capacitation?

  Influx of bicarbonate and calcium
• What is the outermost membrane of the sperm?

  Plasma membrane
• What happens to the outer acrosomal membrane during the acrosomal reaction?

  It disappears after the reaction
• What signals the sperm to start acrosomal exocytosis?

  Calcium influx
• What is the zona pellucida (ZP)?

  A glycoprotein matrix around the egg
• When does the acrosomal reaction begin?

  As sperm moves through the cumulus oophorus
• What is acrosin-GFP?

  A serine protease in the acrosome
• What is the function of acrosin during fertilization?

  It helps sperm digest through membranes