Is fine morphology of the human sperm nuclei affected by in vitro incubation at 37 degrees C?
OBJECTIVE
Incubation of ejaculated spermatozoa at 37 degrees C is recommended for IVF-intracytoplasmic sperm injection. Preselection of sperm cells with morphologically normal nuclei before microinjection, adapted in our laboratory, is usually a time-consuming procedure. Therefore, we aimed to verify whether incubation at 37 degrees C could affect the morphologic integrity of sperm nuclei.


METHODS
Time-kinetics studies testing fine morphology of the sperm nuclei upon prolonged in vitro incubation.


METHODS
Male Fertility Laboratory at Bar-Ilan University, Ramat Gan, Israel.


METHODS
Forty-two males selected at random, who were referred for sperm preselection before ICSI.


METHODS
Morphologic integrity of the sperm nuclei, obtained by motile sperm organelle morphology examination.


RESULTS
After 2 hours of incubation at 37 degrees C a significant decrease occurred in the morphologic integrity of the sperm nuclei, compared with the initial state (4.7% +/- 2.8% vs. 6.8% +/- 3.5%, t = 3.2, P<or=.01). Correspondingly, a significant increase occurred in the frequency of vacuolated nuclei (80.8% +/- 7.2% vs. 75.0% +/- 7.6%, t = -2.8, P<or=.01). No significant morphologic changes in sperm nuclei were observed upon prolonged incubation at 21 degrees C. After 2 hours of incubation, the incidence of spermatozoa with vacuolated nuclei was significantly higher at 37 degrees C compared with 21 degrees C (56.5% +/- 10.8% vs. 45.5% +/- 10%, t = 6.6, P<or=.01).


CONCLUSIONS
Prolonged (>or=2 hours) sperm manipulations for assisted reproduction therapy should be performed at 21 degrees C rather than 37 degrees C.
Peer
Sigal
S
Male Fertility Laboratory, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.
Eltes
Fina
F
Berkovitz
Arie
A
Yehuda
Ronen
R
Itsykson
Pavel
P
Bartoov
Benjamin
B
D002467:Cell Nucleus / Q000648:ultrastructure*; D048430:Cell Shape; D006801:Humans; D007185:Incubators / Q000009:adverse effects; D008297:Male; D013048:Specimen Handling / Q000379:methods*; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology / Q000648:ultrastructure*; D013696:Temperature; D013997:Time Factors; D014617:Vacuoles / Q000648:ultrastructure