Fig. 9 in Sperm evolution in the family Alestidae with comparative data for the genus Chalceus (Ostariophysi: Characiformes)

Fig. 9. Spermatozoon of Chalceus epakros. a, b: longitudinal sections. c, d: transverse sections from top to posterior region. The nucleus (n) is spherical and lies medial to the flagellum (f). The centriolar complex (p, d) and nuclear fossa (arrow) is medial. The proximal centriole (p) is in a right or oblique angle relative to the distal centriole (d). The cytoplasmic canal is present (asterisk). The midpiece (pi) is asymmetrical, and contains only one "c" shape mitochondria (m), vesicles (v) and a cytoplasmic sleeve (arrowhead). The flagellum has lateral fins (fi). Legends: cr: concentric membranous rings, d: distal centriole, e: electron-lucent areas, f: flagellum, fi: flagellar fins, m: mitochondria, n: nucleus, p: proximal centriole, v: vesicle, asterisk: cytoplasmic canal, arrow: nuclear fossa, arrowhead: cytoplasmic sleeve.