Rouleaux formation by spermatozoa in the naked-tail armadillo, Cabassous unicinctus

Spermatozoa from the ductus deferens of a naked-tail armadillo, Cabassous unicinctus, were arranged in rouleaux. The sperm heads were wafer-thin, with the acrosome and nucleus flattened together. Dense subacrosomal material in the equatorial segment of the acrosomal region was present on one surface but not on the other.