# SPERM CAPACITATION AND HYPERACTIVATION

> **NIH NIH R01** · CORNELL UNIVERSITY · 1994 · $86,791

## Abstract

The long-term objectives of this work are to determine how sperm movement
is regulated and how flagellar movement patterns affect the ability of
sperm to reach the site of fertilization and penetrate the oocyte.  We
have focussed our efforts on a movement pattern termed hyperactivation,
because it has been observed to occur in the oviduct near the site of
fertilization.  Our three specific aims at this point are as follows:
(1) Investigate the functions of hyperactivation by comparing the ability
of activated (the movement pattern of sperm in the ejaculate) and
hyperactivated sperm to generate force for pulling away from the
oviductal wall and for penetrating the zona pellucida.  Pulling forces
will be compared by determining the relative force required to hold
activated and hyperactivated sperm onto suction micropipets.  Zona
penetration will be tested by comparing the rates at which acrosome-
reacting activated and hyperactivated sperm penetrate zonae in vitro.
(2) Characterize the mechanism that raises intracellular free Ca2+
([Ca2+]in) to induce hyperactivation.  Based on our observations, we
hypothesize that a different mechanism regulates the calcium influx
associated with hyperactivation than that associated with the acrosome
reaction.  Calcium channels can be characterized by their response to
various organic agents and ions.  We have the ability to estimate
concentrations of [Ca2+]in in various regions of individual, moving
sperm.  These techniques can be used to determine whether an agent
actually affects [Ca2+]in while it is affecting motility.  (3) Determine
whether levels of [Ca2+]in in sperm flagella may be regulated by the
oviduct or zona pellucida.  We have observed that hyperactivation is
initiated in sperm that are attached to the oviductal wall and that only
hyperactivated sperm flagella may be regulated by the oviduct or zona
pellucida.  We have observed that hyperactivation is initiated in sperm
that are attached to the oviductal wall and that only hyperactivated
sperm free themselves from the wall.  It has also been reported that the
pattern of flagellar beating alters when sperm bind to the zona
pellucida.  We hypothesize that elements in the oviductal wall and/or
zona regulate sperm flagellar beating by affecting [Ca2+]in.  [Ca2+]in
will be measured in individual sperm as they attach to oviductal
epithelium and to the zona pellucida.  The information gained may be used
to treat infertility, to monitor the effects of toxins and disease on
fertility, and to develop methods of contraception that act prior to
fertilization.

## Key facts

- **NIH application ID:** 2197843
- **Project number:** 7R01HD019584-09
- **Recipient organization:** CORNELL UNIVERSITY
- **SAM.gov UEI:** G56PUALJ3KT5
- **Principal Investigator:** Susan Stevens Suarez
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $86,791
- **Award type:** 7
- **Project period:** 1985-04-01 → 1996-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2197843

## Citation

> US National Institutes of Health, RePORTER application 2197843, SPERM CAPACITATION AND HYPERACTIVATION (7R01HD019584-09). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2197843. Licensed CC0.

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