Etude ultrastructurale du spermatozoïde du coelacanthe: Latimeria chalumnae

The study of the ultrastructure of the Latimeria chalumnae spermatozoon was carried out using the C3 coelacanth fished on September 24 1953 and preserved in 10% formalin at the Muséum National d'Histoire Naturelle in Paris. The spermatozoon has a tapered acrosome 2.5 μm long. The nucleus is 25 μm in lenght. Its posterior region, which is thinner for about 5 μm, is surrounded by a mitochondrial sheath. The nucleus is lengthwise crossed by a canal which contains three rods which extend to the anterior tip of the acrosome. The two centrioles are located at the base of the nucleus and arranged perpendicular to each other. The flagellum contains a 9 + 2 pattern axoneme and two longitudinal elements opposed to doublets 3 and 8. The ultrastructure of the Latimeria spermatozoon does not show a clear relationship between this fish and another group of fishes or tetrapods.