Dm. Dewire et al., THE EFFECT OF PARTIAL ZONA DISSECTION ON THE FERTILIZING-CAPACITY OF CHRONICALLY OBSTRUCTED MOUSE CAPUT EPIDIDYMAL SPERM, Journal of assisted reproduction and genetics, 11(1), 1994, pp. 43-48
Purpose: Having observed that sperm from the chronically obstructed ca
put epididymis fertilize poorly in vitro, we investigated the effect o
f partial zona dissection (PZD) on fertilization in a murine model of
unilateral proximal epididymal obstruction. Cleavage rates were compar
ed for zona-intact oocytes and PZD oocytes incubated with sperm from t
he following epididymal segments: the obstructed caput, the contralate
ral nonobstructed caput, the contralateral cauda, and a sperm-free pre
paration to control for parthenogenesis. Results: Unilateral epididyma
l obstruction resulted in significantly higher sperm counts in the obs
tructed caput compared to the nonobstructed caput, although there was
no difference in motility. Cleavage rates for ova incubated with sperm
from the obstructed caput and the nonobstructed caput were uniformly
poor and did not differ significantly from those for the sperm-free co
ntrols. Cauda sperm fertilized significantly better than all other spe
rm groups (P < 0.05). Partial zona dissection did not improve cleavage
rates in any group. Conclusion. We conclude that sperm from the chron
ically obstructed caput epididymis, like sperm from the normal caput,
are unable to fertilize ova, and PZD does not enhance this poor fertil
izing capacity. Furthermore, the finding that PZD does not improve the
fertilizing capacity of the presumably mature cauda sperm in our mous
e model suggests that any beneficial effect of PZD may be strain-speci
fic.