Chapter 4
In Situ Nick End-labeling:
Electron Microscopical
YOSHINORI OTSUKI AND YUKO ITO
Introduction
Transmission electron microscopy (TEM) gives us much morphological information on apoptosis, since the concept of apoptosis proposed by Kerr et al. (1972) was based on several characteristic ultrastructural findings. Agarose gel electrophoresis
using extracted DNA is preferentially used in the molecular-biological studies dealing with apoptosis and reveals the apoptotic
nuclear changes such as nucleosomal DNA fragmentation i.e.,
DNA ladder (Arends et al. 1990). In addition to TEM and agarose
gel electrophoresis, in situ end labeling of DNA strand breaks
(ISEL) technique using light microscopy (LM)( conventional
ISEL technique) which labels free 3' -OH ends is widely used
for the discrimination between apoptotic cells and necrotic cells.
Recently, much interest has been focused on the problems related to the specificity of both the agarose gel electrophoresis
of extracted DNA and the conventional ISEL technique in the
detection of cell death, although both are far more convenient
methods than TEM.
• Agarose gel electrophoresis can not demonstrate the DNA
ladder when the sample contains only a few apoptotic cells
(Herrmann et al. 1994)
Correspondence to Yoshinori Otsuki, Osaka Medical College, Department
of Anatomy and Biology, 2-7, Daigaku-machi, Takatsuki, Osaka, 569, Japan
(phone +81-726-831221; fax +81-726-846511; e-mail an1001@art.osakamed. ac. jp); Yuko Ito, Osaka Medical College, Department of Anatomy
and Biology, 2-7, Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan