摘要：

A new histochemical technique, called in situ 3-tailing reaction (ISTR), to detect DNA double strand breaks (DSB) was developed and applied to tissue sections of apoptotic endometrium. To demonstrate DSB, biotin-labeled and unlabeled dATPs with terminal deoxynucleotidyl transferase (TdT) were added to the many 3-hydroxyl termini of DNA fragments generated in the apoptotic cells. For an efficient 3-end labeling, it was necessary to treat the sections with -exonuclease (Ex) prior to the TdT reaction to generate 3-protruding ends. The Ex-TdT reaction specifically labeled nuclear fragments in the apoptotic cells in paraformaldehyde fixed frozen sections. In paraffin sections, pretreatment with proteinase K was effective for 3-tailing reaction. ISTR should be a useful tool for detecting dying cells in both physiological and pathological states.

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