Piabina argentea (Fig. 14 A-E)

In the spermatozoon of Piabina argentea the ovoid nucleus measures 1.52 µ m in the longitudinal axis and 1.2 µ m in the transverse axis. The surrounding strip of cytoplasm has no organelles (Fig. 14A). Nuclear rotation toward the flagellar axis was about 85 degrees (Fig. 14A). The midpiece has a conical shape, measures about 0.6 µ m in length and contains some elongate mitochondria (Fig. 14A,C-E). Information on the endomembrane system is not available, since the specimens of P. argentea have been obtained from ichthyological collections and the gonads were not appropriately preserved for ultrastructural analysis.