title: IVF within microfluidic channels requires lower total numbers and lower concentrations of sperm.
abstract: BACKGROUND
  Microfluidic technology has been utilized in numerous biological applications specifically for miniaturization and simplification of laboratory techniques. We sought to apply microfluidic technology to murine IVF.
  
  
  METHODS
  Microfluidic devices measuring 500 microm wide, 180 microm deep, and 2.25 cm in length were designed and fabricated using poly(dimethylsiloxane) (PDMS). Controls were standard centre-well culture dishes with 500 microl of media, half of which also contained PDMS as a material control. Denuded mouse oocytes were placed into microchannels or centre-well dish controls in groups of 10, then co-incubated overnight with epididymal mouse sperm at various concentrations. Fertilization was assessed and Fisher's exact test was used for statistical analysis (P < 0.05 significant).
  
  
  RESULTS
  Fertilization rates between the two control groups (42%, no PDMS; 41%, with PDMS; not significant) were similar. Fertilization rates for denuded oocytes at standard mouse insemination sperm concentration (1 degrees 10(6) sperm/ml) was poorer in microchannels (12%) than controls (43%; P < 0.001). As insemination concentrations decreased, fertilization rates improved in microchannels with a plateau between 8 degrees 10(4) and 2 degrees 10(4) sperm/ml (4000-1000 total sperm). At these concentrations, combined fertilization rate for denuded oocytes was significantly higher in microchannels than centre-well dishes (27 versus 10%, respectively; P < 0.001), and was not significantly different from corresponding controls with a sperm concentration of 1 degrees 10(6) (37%; P = 0.06).
  
  
  CONCLUSIONS
  Murine IVF can be conducted successfully within microfluidic channels. Lower total numbers and concentrations of sperm are required. Microfluidic devices may ultimately be useful in clinical IVF.
authors.affiliation: Department of Urology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Suh
authors.forename: Xiaoyue
authors.initials: X
authors.lastname: Zhu
authors.forename: Nandita
authors.initials: N
authors.lastname: Phadke
authors.forename: Dana A
authors.initials: DA
authors.lastname: Ohl
authors.forename: Shuichi
authors.initials: S
authors.lastname: Takayama
authors.forename: Gary D
authors.initials: GD
authors.lastname: Smith
mesh_terms: D000818:Animals; D005260:Female; D005307:Fertilization in Vitro / Q000295:instrumentation / Q000379:methods*; D008297:Male; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D008904:Miniaturization; D009865:Oocytes / Q000502:physiology; D013076:Sperm Count; D013094:Spermatozoa / Q000502:physiology