Background: To clarify intranuclear apoptotic changes, we have investigated chromatin organization in apoptotic nuclei of castrated rat prostatic cells by a quick-freezing and deep-etching (QF-DE) method.
Methods: The ventral prostates taken from intact and castrated adult male rats were investigated by light microscopy, in situ end-labeling (ISEL) technique, conventional electron microscopy, and the QF-DE method.
Results: In control nuclei, the chromatin fibers were uniformly distributed and formed a network structure. In apoptotic nuclei, destruction of such chromatin networks was detected, which was clearly seen by the QF-DE method. Although it first appeared spotty in the apoptotic nucleus, definite destruction of the intranuclear network occurred in the nuclear center at later stages, and broken fibrous structures were condensed along the nuclear margin. The ISEL technique was applied to the QF-DE method. Localization of damaged DNA fragments could three-dimensionally be detected on replica membranes.
Conclusions: Intranuclear chromatin organization in apoptotic cell death of rat prostates was observed by the QF-DE method. We could examine early-stage apoptotic nuclei at an electron microscopic level, which would not be clarified by other conventional methods.