What are the steps in sperm fertilization?
capacitation hyperactivation zona binding acrosome reaction zona penetration sperm-oocyte membrane fusion sperm engulfed decondensation of sperm nucleus formation of male pronucleus
What is the process of fertilization of the egg?
Ovulation Sperm-egg membrane fusion Egg activation increase in Ca++ cortical reaction - zona block completion of meiosis formation of female pronucleus Syngamy - fusion of both pronuclei
What is capacitation?
- process of sperm becoming fertile
- occurs in uterus
- must be removed from seminal fluid
- in vitro, wash sperm
- capacitated sperm have the ability to fertilize the egg
What is hyperactivation?
- sperm motility that is characterised by a high amplitude asymmetrical beating pattern of sperm tail
- facilitates sperm-oocyte contact
- occurs in oviduct
- motility pattern becomes frenzied
- linear to non-linear motion
What is zona binding?
- Zona proteins: ZP1, ZP2, ZP3
- Sperm bind ZP3 specifically
- Initiates acrosome reaction
What is the acrosome reaction?
- Fusion of two membranes
- spermatazoal plasma membrane
- outer acrosomal membrane - Acrosin released
- allows sperm to penetrate zona - Exposes equatorial segment
- for fusion with egg
What is sperm-egg fusion?
- Equatorial segment of sperm
- Plasma membrane of egg
- Initiates egg activation
What is fertilization?
- Fertilization occurs in the ampulla of the fallopian tube
- Sperm capacitation
- Swimming & attractants
- Egg contact
- Penetration
- Nuclear fusion
Describe zygote development?
- Cell divisions
- Blastocyst
- Migration to Uterus
- Implantation
Describe egg activation?
- Cortical Reaction exocytosis of cortical granules
- Zona block
- biochemical changes eliminates sperm binding
What is the purpose of IVF?
- Humans: overcome infertility
- male factor: low motility, low count
- female factor: tubal, ovulatory - Animals: end of reproductivity
- more superior animals - Research: IVM with IVF
- many embryos to study techniques: transgenics, cloning
What is gamete intra-fallopian transfer?
sperm and eggs are placed in fallopian tube to allow fertilization in the natural site
- the woman must have at least one normal open fallopian
What is zygote intra fallopian injection?
a woman’s egg is fertilized outside the body then implanted in one of her fallopian tubes
What is intra-uterine sperm injection?
sperm that have been washed and concentrated are placed directly in your uterus the time your ovary releases eggs to be fertilized
- artificial insemination
What is intracytoplasmic sperm injection?
injection of a single sperm into the centre of the egg Overcome fertilization problems: no penetration very low count (<500,000/sample) very low motility (<20% motile)
