Histopathology of mitral Valve prolapsed shows what kind of change?

In myxomatous degeneration of the mitral valve, one or both mitral leaflets are "floppy" and prolapse--they balloon back into the left atrium during systole. Mitral valve prolapse is a primary form of myxomatous mitral degeneration affecting some 0.5% to 2.4% of adults; thus, it is one of the most common forms of valvular hea disease in the Western world. Men and women are equally affected. (Robbins Basic Pathology,9th edition,pg no.403)