Sounds like stretching to me. When the light output isn't intense enough, marijuana stems will elongate. Essentially, they're stretching towards the light to try and receive more of it. The best cure for this is to lower your light source closer to the sprouts. If you're using fluorescents, you can usually get away with having the light just a few inches from the tops of the plants, as they don't get too hot. If you're using an HID system, then you'll need to base the distance on several factors - the wattage of the light, whether or not the lamp is enclosed behind class or air-cooled, ventilation, etc. A good rule of thumb is to put your hand underneath the light and gradually move it up until the heat becomes slightly uncomfortable to you. If it's uncomfortable to the back of your hand, it's probably going to be uncomfortable to your plants.

As for your plants not growing any leaves, it's probably because they've been expending their precious energy producing a longer stem, and don't yet have a strong root system.