03 Fertilization

• Role of calmodulin dependent protein kInase II and calpain

  Degrades cytostatic factor
• Calmodulin activates

  calmodulin dependent protein kInase II and calpain
• Calcium ions released into the frog's membrane bind with

  Calmodulin
• Lifts off the diplotene block in frogs

  Progesterone
• Accomplishments of fertilization

  - completion of second meiotic block

  - restores normal diploid number of chromosomes

  - sex of future embryo is determined

  - genetic variation

  - metabolic activation of fertilized egg
• Penetrates and helps in digesting zona pellucida In rodents

  ZP3 protein
• Penetrates and helps in digesting zona pellucida

  Proteloytic enzymes
• Penetrates the oocyte cytoplasm

  Midpiece
• Digests the corona radiata, zona pellucida and the plasma membrane

  Hyaluronidase
• Length of capacitation for Humans

  5-8 hours
• Length of capacitation for Rabbits

  6 hours
• Length of capacitation for mouse

  1 hour
• Period of conditioning for sperms

  Capacitation
• What are the barriers sperms need to pass through as they are transported in the female reproductive tract

  - natural vaginal acidity

  - thick cervical mucus

  - wide uterus

  - utero-tubal junction
• Pathway of sperm in fertilization

  Upper vaginal canal -> Cervix -> uterus - uterotubal junction -> ampulla of fallopian tube
• Where is the site of insemination in mammals

  Upper vaginal canal
• Where is the fertilization site

  Ampulla
• Around how many days is the oocyte at the vicinity of the uterus

  7-8 days
• How many days does it take for the oocyte to travel from the oviduct to uterus

  4-5 days
• Finger like structures surrounding the ostium

  Fimbriae
• Mouth or opening of the fallopian tube

  Ostium
• Target proteins that result to cellular responses

  Phosphorylates
• Protein kinae c activates

  Exchange of Na+/H+ and increases intracellular pH
• Production of DAG activates

  Protein kinase C
• Coenzyme involved in the synthesis of lipids necessary for the preparation for the fertilized oocyte for the generation of plasma membranes

  NADP+
• Actual pronuclear fusion

  Amphimixis
• What happens when the sperm gets to the oocyte's cytoplasm?

  Head unergoes decondensation and nuclear breakdown to form the male pronucleus
• Activates the release of calcium ions from calcium reserves and triggers cortical reaction


  IP3
• Activation of phospholipase C results to the production of

  Inositol triphosphate and diacylglycerol
• What is activated in the second block to polyspermy

  Phospholipase C
• What is the nature of the second block to polyspermy?

  Chemical
• What is the membrane potential after activation of the cell

  +10 mV
• Membrane potential of a cell at rest

  -50 to -70 mV
• What happens during membrane depolarization

  Sodium influx into the cell
• Happens when the previously inactive oocyte gets activated

  Membrane depolarization
• What is the nature of the first block to polyspermy

  Electrical
• Enzymes that harden the fertilization membrane by cross-linking tyrosine residues of adjacent proteins

  Peroxidases
• Produce osmotic gradients causing water to rush between the vitelline envelope and plasma membrane

  Mucopolysaccharides
• Breaks down molecular bonds between vitelline envelope and plasma membrane

  Proteases
• What are the contents being released during cortical reaction

  - proteases

  - mucopolysaccharides

  - peroxidases