Micromanipulation of Mammalian Gametes

  • Kristen A. Ivani
  • George E. SeidelJr.


Many sperm are deposited in the female reproductive tract, but a very low percentage survive for more than a few hours in a motile condition after copulation; most never come near an egg. In the mouse the average ejaculate contains approximately 58 million sperm (Hogan et al., 1986), but only 17 were found in the ampulla of the oviduct at the time of fertilization (Braden and Austin, 1954). Similar phenomena occur in other mammalian species. The proportion of sperm capable of fertilizing ova and supporting normal development is unknown. Despite development of sophisticated techniques and information on mammalian in vitro fertilization, we still know very little about the manner in which a single sperm is selected to fertilize each oocyte. Much of what we know results from in vitro studies in which thousands of sperm are added to a few oocytes; unfortunately, this approach gives us little information about the behavior of the fertilizing spermatozoon. In order to refine in vitro fertilization systems to more closely mimic fertilization in vivo,one must deal with “dilution effects. ” At very low sperm concentrations, sperm frequently lose their motility and, hence, their subsequent fertilizing ability, probably because of dilution of important components of reproductive tract fluids.


Zona Pellucida Nuclear Transplantation Germinal Vesicle Mouse Oocyte Sperm Nucleus 
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Copyright information

© Springer Science+Business Media New York 1991

Authors and Affiliations

  • Kristen A. Ivani
    • 1
  • George E. SeidelJr.
    • 1
  1. 1.Animal Reproduction and Biotechnology LaboratoryColorado State UniversityFort CollinsUSA

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