Comparative ultrastructure of the spermatogenesis of three species of Poecilosclerida (Porifera, Demospongiae).

Vivian Vasconcellos (1) , Philippe V Willenz (2) , Alexander Ereskovsky (3) , Emilio Lanna (1)

1 UFBA - Universidade Federal da Bahia
2 ULB - Université libre de Bruxelles
3 IMBE - Institut méditerranéen de biodiversité et d'écologie marine et continentale

The spermatogenesis of Porifera is still relatively poorly understood. In the past, it was accepted that all species presented a primitive-type spermatozoon, lacking special structures and acrosome. Nonetheless, a very peculiar spermatogenesis resulting in V-shaped spermatozoonwith acrosome was found in Poecilosclerida, calling into question the reproductive and evolutionary aspects of Porifera.We investigated theultrastructure of the spermatogenesis of three different species of Poecilosclerida (Porifera, Demospongiae):Iophon proximum, I. piceus and Tedania ignis. In all three species,spermatogenesis wassynchronizedwithin the spermatic cysts. Iophon proximumand T. ignispresented elongated sperm cells, but in I. piceus their shape was globular, suggesting a primitive spermatozoon. A structure resembling an acrosome was only found in T.ignis. Apparently, the type of spermatozoid in poeciloscleridsis not dictated by the phylogeny nor the environment. Nonetheless, we are proposing that the modified type of spermatozoon is the ancestral state in Poecilosclerida.

Keywords: Reproduction; Sponges; Gametogenesis; Modified Spermatozoa; Acrosome

Domains: Life Sciences [q-bio]; Development Biology; Life Sciences [q-bio]; Development Biology; Gametogenesis

Vivian Vasconcellos, Philippe V Willenz, Alexander Ereskovsky, Emilio Lanna. Comparative ultrastructure of the spermatogenesis of three species of Poecilosclerida (Porifera, Demospongiae).. Zoomorphology, 2019, 138 (1), pp.1-12. ⟨10.1007/s00435-018-0429-4⟩. ⟨hal-02012263⟩