Apoptotic Schwann cells in leprosy tissues. DNA strand breaks were detected on the basis of terminal deoxynucleotidyltransferase (Tdt) activity and were found in cells with a morphology typical of Schwann cells in leprosy tissues. Arrows indicate apoptosis-positive cells with wavy nuclei, characteristic of Schwann cells. Original magnifications, ×100 (left and middle panels) and ×400 (right panels). Tdt−, no enzyme added (negative control); Tdt+, Tdt enzyme added; T-lep, tuberculoid leprosy.