Parthenogenetic activation of pig oocytes with calcium ionophore and the block to sperm penetration after activation
Calcium ionophore A23187 can parthenogenetically activate oocytes in many animals. The present study was designed to analyze functionally the mechanism of A23187 activation of pig oocytes matured in vitro. In experiment 1, effects of the concentration of A23187 on intracellular calcium transients, c...
Saved in:
Published in: | Biology of reproduction 1998-06, Vol.58 (6), p.1357-1366 |
---|---|
Main Authors: | , , , , |
Format: | Article |
Language: | eng |
Subjects: | |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | Calcium ionophore A23187 can parthenogenetically activate oocytes in many animals. The present study was designed to analyze
functionally the mechanism of A23187 activation of pig oocytes matured in vitro. In experiment 1, effects of the concentration
of A23187 on intracellular calcium transients, cortical granule (CG) exocytosis, nuclear activation, and zona reaction, which
was determined by zona hardening and sperm penetrability, were examined. Cumulus-free oocytes were exposed to 0-100 microM
A23187 for 5 min. It was found that the amplitude of the intracellular calcium transients, percentage of CG exocytosis, and
percentage of pronuclear formation were increased in a concentration-dependent manner. The time for dissolution of zona pellucida
(ZP) was increased in the oocytes treated with 25-100 microM A23187. Penetration of ZP-intact oocytes by spermatozoa was decreased
and only 3-4% of oocytes were penetrated by spermatozoa after 50-100 microM A23187 treatment. In experiment 2, oocytes were
treated with 100 microM A23187 for 5 min and then cultured for 10 min or 3.5 h before insemination. No difference in penetration
rates was observed between the two groups of oocytes (12.0% vs. 12.2%), but the penetration rates were significantly lower
than those in controls (85.2% vs. 82.4%). In experiment 3, treatment of oocytes with 100 microM A23187 for 5 min was followed
by removal of the ZP from a portion of the oocytes. ZP-intact and ZP-free oocytes were then inseminated for examination of
sperm penetration. One of 65 (2%) oocytes with ZP and 48 of 52 (92%) oocytes without ZP were penetrated by spermatozoa. These
results indicate that activation of pig oocytes by A23187 is the result of A23187-induced intracellular calcium increase and
that A23187-induced cortical reaction can prevent sperm penetration of ZP-intact oocytes, but not ZP-free oocytes. |
---|---|
ISSN: | 0006-3363 1529-7268 |