Morphology and fine structure of Barbus barbus (Teleostei: Cyprinidae) spermatozoa

Morphology and fine structure of Barbus barbus L 1758 spermatozoa were studied using scanning (SEM) and transmission (TEM) electron microscopy. The results confirm that spermatozoa exhibit morphological features typical to all teleost fishes. They are differentiated into a head, a midpiece and a flagellum with the typical '9 + 2' pairs of microtubules. Both dynein arms are present in the flagellum. The spermatozoa have spherical nuclei, 4–6 mitochondria located in the postnuclear cytoplasmic region and centriolar complex (proximal and distal centrioles). Total length, head width, length of midpiece and length of flagellum were measured to be 56.35 ± 7.42, 1.80 ± 0.06, 0.48 ± 0.14 and 54.30 ± 6.97 μm, respectively. Highly significant linear correlation was observed between posterior and anterior width of midpiece (P < 0.01). Principal component analysis (PCA) was used to explore which parameters can explain the individual variation of sperm morphology. About 44% of the total accumulated variance was absorbed by the analysis of the two first components, distinguishing different groups of parameters related to head and midpiece. The lengths of flagellum and head are more isolated; indicating that the individual variation of sperm morphology depends on these two parameters. Comparing the results of this study with information on cyprinids spermatozoa reveals that the number of mitochondria and the length of the flagellum are good characters to characterize spermatozoa of the Cyprinidae in a phylogenetic arrangement.