Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction

Abstract Background The mechanisms enabling sperm to locate unfertilized eggs within the fallopian tubes remain a subject of debate in reproductive biology. Previous studies using polytocous mammals observed a 1:1 sperm-egg ratio within the ampulla at the time of fertilization. From these observatio...

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Main Authors: Eva Stickler, Matteo Avella
Format: Article
Language:English
Published: BMC 2024-12-01
Series:Journal of Translational Medicine
Online Access:https://doi.org/10.1186/s12967-024-05948-4
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author Eva Stickler
Matteo Avella
author_facet Eva Stickler
Matteo Avella
author_sort Eva Stickler
collection DOAJ
description Abstract Background The mechanisms enabling sperm to locate unfertilized eggs within the fallopian tubes remain a subject of debate in reproductive biology. Previous studies using polytocous mammals observed a 1:1 sperm-egg ratio within the ampulla at the time of fertilization. From these observations, it is hypothesized that this mechanism could be linked to sperm-egg fusion, such that unfertilized eggs may attract sperm until fusion occurs, whereupon the attraction ceases. Methods To test this, fertile male mice were mated with infertile homozygous Cd9 Null females, whose eggs cannot fuse with sperm, leading to the accumulation of supernumerary sperm in the perivitelline space. Fertile heterozygous Cd9 Het females, were used as controls. Results The results revealed that both Cd9 Null and Cd9 Het females ovulated similar numbers of eggs (6.53 ± 0.61 vs. 5.50 ± 0.53 eggs/ampulla). The majority of eggs produced by Cd9 Het females were fertilized by one single sperm, without any additional sperm found bound to the zona or within the perivitelline space. In contrast, most of the eggs ovulated by Cd9 Null females either showed an accumulation of supernumerary sperm within in the perivitelline space or showed no sperm bound to the zona nor present within the perivitelline space. Conclusions These findings indicate that genetic ablation of Cd9 leads to an imbalance in the 1:1 sperm-egg ratio observed within the ampulla. This information may set the foundation for future studies with the aim to identify the specific mechanisms that sperm use to locate unfertilized eggs and whether they become ineffective when gamete fusion is prevented.
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spelling doaj-art-fa898399e8cc41ccbf4d621d5b092f8a2024-12-22T12:44:34ZengBMCJournal of Translational Medicine1479-58762024-12-012211610.1186/s12967-024-05948-4Disruption of gamete fusion alters the sperm-egg ratio at gamete interactionEva Stickler0Matteo Avella1Department of Biological Science, University of TulsaDepartment of Biological Science, University of TulsaAbstract Background The mechanisms enabling sperm to locate unfertilized eggs within the fallopian tubes remain a subject of debate in reproductive biology. Previous studies using polytocous mammals observed a 1:1 sperm-egg ratio within the ampulla at the time of fertilization. From these observations, it is hypothesized that this mechanism could be linked to sperm-egg fusion, such that unfertilized eggs may attract sperm until fusion occurs, whereupon the attraction ceases. Methods To test this, fertile male mice were mated with infertile homozygous Cd9 Null females, whose eggs cannot fuse with sperm, leading to the accumulation of supernumerary sperm in the perivitelline space. Fertile heterozygous Cd9 Het females, were used as controls. Results The results revealed that both Cd9 Null and Cd9 Het females ovulated similar numbers of eggs (6.53 ± 0.61 vs. 5.50 ± 0.53 eggs/ampulla). The majority of eggs produced by Cd9 Het females were fertilized by one single sperm, without any additional sperm found bound to the zona or within the perivitelline space. In contrast, most of the eggs ovulated by Cd9 Null females either showed an accumulation of supernumerary sperm within in the perivitelline space or showed no sperm bound to the zona nor present within the perivitelline space. Conclusions These findings indicate that genetic ablation of Cd9 leads to an imbalance in the 1:1 sperm-egg ratio observed within the ampulla. This information may set the foundation for future studies with the aim to identify the specific mechanisms that sperm use to locate unfertilized eggs and whether they become ineffective when gamete fusion is prevented.https://doi.org/10.1186/s12967-024-05948-4
spellingShingle Eva Stickler
Matteo Avella
Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction
Journal of Translational Medicine
title Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction
title_full Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction
title_fullStr Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction
title_full_unstemmed Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction
title_short Disruption of gamete fusion alters the sperm-egg ratio at gamete interaction
title_sort disruption of gamete fusion alters the sperm egg ratio at gamete interaction
url https://doi.org/10.1186/s12967-024-05948-4
work_keys_str_mv AT evastickler disruptionofgametefusionaltersthespermeggratioatgameteinteraction
AT matteoavella disruptionofgametefusionaltersthespermeggratioatgameteinteraction