Figure 1.

Sperm chromatin structure and SDF assays. (A) Intact sperm chromatin is condensed into protamine-bound toroids that are linked by short stretches of the chromatin and anchored to the nuclear matrix. TB, AB and CMA3 tests all assay DNA in its intact state; (B) the TUNEL assay also measures DNA damage in situ; (C) the SCSA and AO tests assay sperm chromatin from which the histones have been removed; (D) the Comet assay assesses DNA from which all the protamines and toroids have been removed. This image is modified from one by Gawecka, et al. (10). SCSA, sperm chromatin structure assay; TUNEL, Terminal deoxynucleotidyl transferase dUTP nick end labeling.