DNA fragmentation during the programmed cell death in the chick limb buds.

Programmed cell death plays a crucial role in limb morphogenesis of amniote. So far, there has been no biochemical evidence found to support the fact that embryonic cell death is apoptosis. In this report, we show the oligo-nucleosomal ladder pattern of DNA obtained from interdigital tissues of chick leg buds, indicating that programmed cell death has some features that are common to those involved in apoptosis. Furthermore, cells exhibiting DNA fragmentation were detected by using a method of in situ end labeling of DNA breaks. The distribution pattern of those cells corresponded well to those of programmed-dead cells situated within the interdigital mesenchyme of the leg bud.