Patterns of intracellular calcium oscillations in horse oocytes fertilized by intracytoplasmic sperm injection: possible explanations for the low success of this assisted reproduction technique in the horse.
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.
Publication Date: 2003-12-03 PubMed ID: 14656727DOI: 10.1095/biolreprod.103.021485Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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This research article investigates why the success rate of intracytoplasmic sperm injection (ICSI), an assisted reproduction technique, is surprisingly low in horses. The results suggest that horse oocytes may have a problem responding to the release of the ‘sperm factor’ that initiates intracellular calcium oscillations and embryonic development.
Investigation of Ca2+ Oscillations in Fertilized Horse Oocytes
- The study began by using ICSI, where a single sperm is injected directly into an egg, to explore the ‘sperm factor’ induced intracellular calcium (Ca2+) signaling in horse oocytes. Calcium oscillations are necessary for oocyte activation and embryonic development and can indicate successful fertilization.
- It was found that very few oocytes showed Ca2+ responses regardless of their origin, suggesting that there may be a problem with the release of the sperm factor into the oocyte.
- To test this hypothesis, the researchers permeabilized sperm membranes with Triton-X or by sonication, but these methods did not improve the deficient Ca2+ responses, indicating that the problem lies downstream of the sperm factor release.
Testing Sperm Factor Function
- The researchers then considered that the issues might be due to a failure in a process that is required for the sperm factor to function correctly.
- To test this idea, they fused ICSI-fertilized horse oocytes with unfertilized mouse oocytes, which are known to respond to injection of horse sperm with Ca2+ oscillations.
- The paired oocytes consistently displayed Ca2+ responses, showing that the sperm factor is released appropriately, but horse oocytes are unresponsive or unable to provide the correct substrate for the sperm factor to initiate the necessary oscillations.
Implications for Assisted Reproduction Techniques
- The findings suggest that the low success rate of ICSI in horses could be due to a problem with the horse oocytes’ response to the sperm factor, not with the sperm factor release.
- This indicates a need for further research into the molecular mechanisms involved in fertilization in horse oocytes.
- The results may ultimately aid in improving the success rates of ICSI and other assisted reproduction techniques in horses and potentially other livestock species.
Cite This Article
APA
Bedford SJ, Kurokawa M, Hinrichs K, Fissore RA.
(2003).
Patterns of intracellular calcium oscillations in horse oocytes fertilized by intracytoplasmic sperm injection: possible explanations for the low success of this assisted reproduction technique in the horse.
Biol Reprod, 70(4), 936-944.
https://doi.org/10.1095/biolreprod.103.021485 Publication
Researcher Affiliations
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA.
MeSH Terms
- Animals
- Calcium / metabolism
- Calcium Signaling
- Cells, Cultured
- Cellular Senescence
- Female
- Fertilization
- Horses / physiology
- Intracellular Fluid / metabolism
- Male
- Mice
- Mice, Inbred Strains
- Oocytes / metabolism
- Oocytes / physiology
- Osmolar Concentration
- Reproductive Techniques, Assisted / standards
- Sperm Injections, Intracytoplasmic
- Spermatozoa / metabolism
- Treatment Outcome
Citations
This article has been cited 5 times.- Fakhar-I-Adil M, Angel-Velez D, Araftpoor E, Amin QA, Hedia M, Bühler M, Gevaert K, Menten B, Van Soom A, Chuva de Sousa Lopes SM, Stoop D, De Roo C, Smits K, Heindryckx B. Biphasic CAPA-IVM Improves Equine Oocyte Quality and Subsequent Embryo Development Without Inducing Genetic Aberrations. Int J Mol Sci 2025 Jun 8;26(12).
- Gonzalez-Castro RA, Carnevale EM. Phospholipase C Zeta 1 (PLCZ1): The Function and Potential for Fertility Assessment and In Vitro Embryo Production in Cattle and Horses. Vet Sci 2023 Dec 11;10(12).
- Gimeno BF, Bariani MV, Laiz-Quiroga L, Martínez-León E, Von-Meyeren M, Rey O, Mutto AÁ, Osycka-Salut CE. Effects of In Vitro Interactions of Oviduct Epithelial Cells with Frozen-Thawed Stallion Spermatozoa on Their Motility, Viability and Capacitation Status. Animals (Basel) 2021 Jan 3;11(1).
- Stein P, Savy V, Williams AM, Williams CJ. Modulators of calcium signalling at fertilization. Open Biol 2020 Jul;10(7):200118.
- Morozumi K, Shikano T, Miyazaki S, Yanagimachi R. Simultaneous removal of sperm plasma membrane and acrosome before intracytoplasmic sperm injection improves oocyte activation/embryonic development. Proc Natl Acad Sci U S A 2006 Nov 21;103(47):17661-6.
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