Jquery sliding toggle help

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C#

Hello everyone,
I am stuck with a problem. I have used this jQuery code for toggling 2 divs with a slide effect:

<script type=text/javascript>
    $(document).ready(function() {
        //hide the all of the element with class msg_body
        $(".msg_body", "litCategoryName").hide();
        //toggle the componenet with class msg_body
        $(".msg_head").click(function() {
            $(this).next(".msg_body").slideToggle(50);
        });
    });
</script>

It's working fine, but I want to display a + or - too when someone expands and collapses the 2 divs.
Can anyone guide me on how to achieve this.

Thanks in advance!