Rigorous thermal control during intracytoplasmic sperm injection stabilizes the meiotic spindle and improves fertilization and pregnancy rates.
OBJECTIVE
To examine the effects of different thermodynamic control systems on the temperature stability of human eggs during in vitro manipulation, with the integrity of meiotic spindles imaged using the LC-PolScope (Cambridge Research & Instrumentation, Inc., Woburn, MA).


METHODS
We performed intracytoplasmic sperm injection (ICSI) and/or imaging of eggs with the temperature regulated by three different systems: thermostated coverslip (system 1), thermostated coverslip combined with objective heater (system 2), and conventional stage warmer (system 3).


METHODS
Academic in vitro fertilization clinic.


METHODS
Oocytes were aspirated from stimulated ovaries of patients undergoing oocyte retrieval for ICSI.


METHODS
Measurement of temperature regulation in media surrounding eggs during in vitro manipulation and imaging.


METHODS
Rate of oocytes with spindles, fertilization rates, and clinical pregnancy rates after ICSI.


RESULTS
We imaged spindles in more oocytes with system 2 (81.2%) than with system 1 (61.4%). Spindles could not be imaged for system 3 because of technical limitations. Fertilization rates were significantly higher when oocytes were imaged and used for ICSI with system 2 (78.8%) than with system 1 (56.7%) or system 3 (64.0%). Most importantly, a significantly higher clinical pregnancy rate was observed when oocytes were manipulated with system 2 (51.7%) than with system 1 (25.0%) or system 3 (23.1%). No differences were found in average ages, number of previous cycles, number of eggs, or day 3 FSH or E2 levels among groups.


CONCLUSIONS
Imaging meiotic spindles with the PolScope provides an intracellular thermostat during ICSI. Rigorous thermal control during ICSI stabilized spindles and increased the fertilization and clinical pregnancy rates achieved after ICSI. The presence of birefringent spindles in living human eggs served as a monitor for in vitro conditions.
Wang
Wei-Hua
WH
Houston Fertility Institute, Tomball Regional Hospital, Tomball, Texas, USA.
Meng
Li
L
Hackett
Richard J
RJ
Oldenbourg
Rudolf
R
Keefe
David L
DL
D000328:Adult; D005260:Female; D005306:Fertilization / Q000502:physiology; D005307:Fertilization in Vitro; D006361:Heating / Q000295:instrumentation*; D006801:Humans; D008540:Meiosis; D009865:Oocytes / Q000502:physiology / Q000648:ultrastructure; D011247:Pregnancy; D018873:Pregnancy Rate; D020554:Sperm Injections, Intracytoplasmic / Q000295:instrumentation* / Q000379:methods*; D008941:Spindle Apparatus / Q000502:physiology* / Q000648:ultrastructure; D013816:Thermodynamics