|
|
||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Abstract
In all species studied, fertilization induces
intracellular Ca2+
([Ca2+]i) oscillations required for
oocyte activation and embryonic development. This species-
specific pattern has not been studied in the equine,
partly due to the difficulties linked to in vitro
fertilization in this species. Therefore, the objective
of this study was to use intracytoplasmic sperm injection
(ICSI) to investigate fertilization-induced
[Ca2+]i signaling and, possibly,
ascertain problems linked to the success of this
technology in the horse. In vivo- and in vitro-matured
mare oocytes were injected with a single motile stallion
sperm. Few oocytes displayed
[Ca2+]i responses regardless of
oocyte source and we hypothesized that this may result
from insufficient release of the sperm-borne active
molecule (sperm factor) into the oocyte. However,
permeabilization of sperm membranes with Triton-X or by
sonication did not alleviate the deficient
[Ca2+]i responses in mare oocytes.
Thus we hypothesized that a step downstream of release,
possibly required for sperm factor function, is not
appropriately accomplished in horse oocytes. To test this,
ICSI-fertilized horse oocytes were fused to unfertilized
mouse oocytes, which are known to respond with
[Ca2+]i oscillations to injection
of stallion sperm, and [Ca2+]i
monitoring was performed. Such pairs consistently
displayed [Ca2+]i responses
demonstrating that the sperm factor is appropriately
released into the ooplasm of horse oocytes, but that
these are unable to activate and/or provide the
appropriate substrate that is required for the sperm
factor delivered by ICSI to initiate oscillations. These
findings may have implications to improve the success of
ICSI in the equine and other livestock species.
Key words:
Gamete Biology
Assisted Reproductive Technology
Calcium
Fertilization
Sperm
This article has been cited by other articles:
![]() |
K Hinrichs, Y H Choi, D D Varner, and D L Hartman Production of cloned horse foals using roscovitine-treated donor cells and activation with sperm extract and/or ionomycin Reproduction, August 1, 2007; 134(2): 319 - 325. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. B. Wortzman-Show, M. Kurokawa, R. A. Fissore, and J. P. Evans Calcium and sperm components in the establishment of the membrane block to polyspermy: studies of ICSI and activation with sperm factor Mol. Hum. Reprod., August 1, 2007; 13(8): 557 - 565. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Morozumi, T. Shikano, S. Miyazaki, and R. Yanagimachi From the Cover: Simultaneous removal of sperm plasma membrane and acrosome before intracytoplasmic sperm injection improves oocyte activation/embryonic development PNAS, November 21, 2006; 103(47): 17661 - 17666. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |