Fig. 15 in Spermatic characteristics and sperm evolution on the subfamily Stevardiinae (Ostariophysi: Characiformes: Characidae)

Fig. 15. Spermatozoa of Rhinobrycon negrensis. A: Longitudinal section of spermatozoa. Note the position of the nucleus (n) in relation to the flagellar axis and to proximal (p) and distal (d) centrioles, the eccentric position of the double nuclear fossa (double arrow), the midpiece and the cytoplasmic canal (*) containing the initial segment of the flagellum (f). B-C: Longitudinal sections of the midpiece exposing the lateral position of the distal centriole (d), the cytoplasmic canal (*) and the flagellum (f), the distribution of the few elongate mitochondria (m) accumulated in larger portion of the midpiece, few large vesicles peripherally distributed (v). D-E: Cross sections at different levels of the asymmetric midpiece showing the mitochondria (m) and a few vesicles (v). Information on the endomembrane system was not preserved due the specimens of R. negrensis herein analysis have been obtained from ichthyological collections.