Chromatin ultrastructure changes during spermatogenesis in armadillos.

The chromatin fibres of the male gamete nucleus of Dasypus novemcinctus contain fibrils. Measurements indicate that the chromatin fibre diameter and the number of fibrils within the fibre increase, whereas the diameter of the fibrils decreases during spermiogenesis. It is suggested that the fibrils represent a DNA-protein complex. It is further suggested that the increased fibre diameter, and the increased number of fibrils correlates with the formation of larger fibres during the condensation of the spermatid nucleus, whereas the decrease in fibril diameter is correlated with the replacement of histones with new low molecular weight acid-soluble proteins.