Fig. 3. Serrasalmus maculatus spermatozoa. A in Spermiogenesis and spermatozoa ultrastructure in the Serrasalminae (Ostariophysi: Characiformes) with further evidence on the relationships of the piranhas and pacus

Fig. 3. Serrasalmus maculatus spermatozoa. A - Spermatozoa in longitudinal section. B - Flagellum in longitudinal section. C - Longitudinal section of the nucleus at the nuclear fossa region. D to J - Cross sections in different levels of midpiece. K and L - Flagella in cross sections. Note the vesicles in the initial segment of the flagella. Scale bars A = 0.5 µm; A/Inset = 0.2 µm; B- C = 0.45 µm; D = 0.7 µm; E and F = 0.4 µm; G = 0.5 µm; H and I = 0.55 µm; J = 0.4 µm; K = 0.35 µm; L = 0.6 µm. A: axoneme; C: centriole; 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.