Related Experiment Video
Updated: Aug 2, 2026
A Seminiferous Tubule Squash Technique for the Cytological Analysis of Spermatogenesis Using the Mouse Model
Published on: February 6, 2018
Relationship between the M42 antigen of mouse sperm and the acrosome reaction induced by ZP3
L Leyton1, A Robinson, P Saling
1Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina 27710.
Abstract:
A murine monoclonal antibody, M42 mAb, directed against 200/220 Kd protein of mouse sperm, has been employed to study the molecular events of gamete interaction. We have reported previously that M42 mAb blocks mouse fertilization in a zona-dependent manner; the reagent specifically inhibits physiologically induced (zonae), but not pharmacologically induced (A23187), acrosome reactions in mouse sperm. Using solubilized mouse zonae pellucidae and purified ZP3, we demonstrate that M42 mAb inhibits acrosome reactions (ARs) induced by ZP3 to the same extent as those induced by total zonae. We have also studied AR inhibition using the fluorescent antibiotic chlortetracycline (CTC), which permits visualization of three different acrosomal patterns during the AR. In the presence of M42 IgG, greater than 70% of capacitated sperm treated with zonae are arrested in the acrosome-intact state (B-pattern), in contrast to the majority of sperm (60-70%) in the absence of M42 IgG, which progress through the intermediate phase (S-pattern) to the fully acrosome-reacted (AR-pattern) state. Incubation of sperm with zona proteins modified by incubating eggs with phorbol esters arrests sperm in the S-pattern (Y. Endo, R.M. Schultz, and G.S. Kopf, 1987, Dev. Biol. 119, 199-209). We show that once sperm have reached such a state, M42 mAb no longer exerts an inhibitory effect. The addition of unmodified ZP to S-pattern sperm permits the completion of the acrosome reaction. These results indicate that M42 mAb blocks an early step in the AR cascade and that M42 mAb is unable to prevent subsequent events of this cascade once it has been initiated.
Insights
A monoclonal antibody, M42 mAb, blocks mouse fertilization by inhibiting an early step in the acrosome reaction (AR) triggered by zona pellucida proteins. It prevents sperm from initiating the AR but cannot stop later stages once they begin.
Area of Science:
- Reproductive biology
- Immunology
- Cell signaling
Background:
- Fertilization involves complex molecular interactions between sperm and egg.
- The acrosome reaction (AR) is crucial for sperm penetration of the egg's outer layers.
- Understanding AR regulation is key to reproductive science.
Purpose of the Study:
- To investigate the mechanism by which M42 mAb inhibits mouse fertilization.
- To determine the specific stage of the acrosome reaction targeted by M42 mAb.
- To elucidate the role of sperm-zona pellucida interactions in initiating the AR.
Main Methods:
- Utilized a murine monoclonal antibody (M42 mAb) targeting a mouse sperm protein.
- Assessed AR inhibition using solubilized zonae pellucidae and purified ZP3.
- Employed chlortetracycline (CTC) fluorescence assay to visualize acrosomal states.
- Studied the effect of M42 mAb on sperm treated with modified zona proteins.
Main Results:
- M42 mAb inhibits AR induced by both zonae pellucidae and purified ZP3.
- M42 mAb prevents capacitated sperm from initiating the AR, arresting them in an acrosome-intact state.
- The antibody's inhibitory effect is lost once sperm reach an intermediate acrosomal reaction state (S-pattern).
- M42 mAb does not affect the completion of AR in sperm already in the S-pattern.
Conclusions:
- M42 mAb specifically blocks an early, critical step in the acrosome reaction cascade.
- The antibody's target protein is involved in the initial signaling events triggered by zona pellucida binding.
- M42 mAb provides a valuable tool for dissecting the molecular mechanisms of sperm-egg interaction and fertilization.
