Equivalent of "parentNode" in internet explorer

Question

I wrote some code that modifies the images on a webpage. Works with firefox and safari. But tryingto get it to work with Internet explorer has got me stumped. What is the equivalent of "parentNode" in explorer? Or how does one trick it into working?

images = document.getElementsByTagName('img')
parms = {};

for (a=0;a < images.length;a++){
    parent = images[a].parentNode; // <-- What to substitute for explorer?
    parms[a] = {};
    parms[a].bigsrc=parent.getAttribute("href");
    parms[a].w_o = images[a].width;
    parms[a].h_o = images[a].height;
    parms[a].IsBig = false;
    parms[a].loaded = false;
    images[a].border=0;
    parent.setAttribute("href","javascript:MakeBig('"+a+"')");
}

Solution

parentNode works fine in IE (except in certain cases, very likely irrelevant here). The error is almost certainly elsewhere in your code.