Fig. 4. Mylossoma duriventre spermatozoa. A in Spermiogenesis and spermatozoa ultrastructure in the Serrasalminae (Ostariophysi: Characiformes) with further evidence on the relationships of the piranhas and pacus

Fig. 4. Mylossoma duriventre spermatozoa. A - Spermatozoa in longitudinal section. B and C - Longitudinal sections of the nuclear fossa region. D - Midpiece in longitudinal section. E to H - Midpiece in cross sections. I - Flagellum in longitudinal section. J and K - Flagella in cross sections. Scale bars, A = 0.55 µm; B = 0.6 µm; C = 0.35 µm; D = 0.6 µm; E - F = 0.45 µm; G = 0.35 µm; H = 0.4 µm; I = 0.5 µm; J = 0.3 µm; K = 0.25 µm. A: axoneme; D: distal centriole; F: flagellum; M: mitochondria; N: nucleus; P: proximal centriole; V: vesicle; Asterisk: fins; Arrow: electron dense material; Arrowhead: cytoplasmic canal; Double arrow: nuclear fossa; Star: cytoplasmic sleeve.