# OOCYTE CORTICAL MATURATION AND GRANULE ACTIVATION

> **NIH NIH R01** · TUFTS UNIVERSITY BOSTON · 1994 · $136,807

## Abstract

Studies in a number of mammals indicate that 1-5% of fertilized eggs
develop abnormally into triploid embryonic abortuses.  In the human this is
primarily due to fertilization by more than one sperm.  The egg's primary
means of preventing polyspermy is the fertilization-associated release of
cortical granules (CGs) whose contents biochemically modify the egg's zona
pellucida making it less penetrable to sperm.

In antral follicle oocytes (pre-metaphase II) which have not completed
cytoplasmic maturation, one major cause of polyspermy appears to be their
incompetence to undergo CG release.  Preliminary evidence indicates that
this incompetence involves the activation mechanism which includes
intracellular calcium (Ca) and protein kinase C (PKC).  The long-range
goals of this proposal are to determine the causes for this incompetence in
terms of Ca and PKC regulation as well as more accurately assess when
competence develops in the mouse oocyte.  The following are specific aims:

1.  To determine when the oocyte develops the ability to undergo sperm-
induced CG release.  At appropriate stages of meiotic maturation, sperm-
induced CG release will be assayed by % CG loss [quantitative image
analysis(QIA)], by biochemical analysis of the zona (protein ZP2), and by
% monospermic (vs polyspermic) fertilization.

2.  To analyse the oocyte's competence to store and respond to
intracellular Ca during meiotic maturation.  The development of cellular
components involved in calcium regulation will be analyzed with specific
fluorescent probes and QIA.  The ability of the developing oocyte to
undergo CG loss in response to (microinjected) intracellular calcium will
be assessed.

3.  To analyse the oocyte's competence to undergo CG release in response to
protein kinase C activators during meiotic maturation.  At appropriate
stages of maturation, the ability of PKC agonists to induce CG release will
be investigated by QIA and ZP2 analysis.

4.  To test for the synergism of Ca and PKC agonists in activating the
pathways leading to CG loss.  Synergism will be investigated in mature eggs
and, if found, its development will be traced during meiotic maturation.

These studies should result in 1) a more detailed explanation of the
mechanism of egg and CG activation, 2) an identification of the stages of
oocyte maturation which are most susceptable to polyspermic fertilization,
3) at least one likely scientific explanation for the origin of abnormal
triploid abortuses observed in some mammalian species.

## Key facts

- **NIH application ID:** 2199080
- **Project number:** 5R01HD024191-06
- **Recipient organization:** TUFTS UNIVERSITY BOSTON
- **SAM.gov UEI:** C1F5LNUF7W86
- **Principal Investigator:** THOMAS W DUCIBELLA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $136,807
- **Award type:** 5
- **Project period:** 1988-07-01 → 1996-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2199080

## Citation

> US National Institutes of Health, RePORTER application 2199080, OOCYTE CORTICAL MATURATION AND GRANULE ACTIVATION (5R01HD024191-06). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2199080. Licensed CC0.

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