Ultrastructure of grey mullet (Mugil cephalus, Linnaeus, 1758) spermatozoa as revealed from light, scanning and transmission electron microscopy

Spermatozoa morphology and fine structure were studied in the grey mullet, Mugil cephalus using light, scanning and transmission electron microscopy. Light microscopy observations indicate a semi-cystic type of spermatogenesis in the testis. The electron microscopy micrograph showed that the spermatozoon of M. cephalus is uniflagellated (total length 5.78 +/- 1.26 mu m), differentiated into an ovoid-shaped head without acrosome (1.80 +/- 0.35 mu m in length and 1.91 +/- 0.30 mu m in diameter), with a short midpiece and a long cylindrical flagellar tail (length 3.60 +/- 0.50 mu m). The midpiece is characterized by the presence of four to five vacuoles, a cytoplasmic canal, two centriole and two spherical mitochondria having a flat type of cristae. Chromatin granules of the nucleus form an electron-dense homogeneous mass. The flagellum consists of nine peripheral microtubules and a central pair (9 + 2) surrounded by the plasma membrane with side fins. The results confirm that spermatozoa of M. cephalus are perciform or teleostean type II. Information generated from the present study will be useful in taxonomic classification, cryopreservation and breeding work.