Abstract
Mesodasys adenotubulatus Hummon, Todaro and Tongiorgi 1993 is a simultaneous hermaphrodite. Two club-shaped testes extend along the sides of the anterior intestine and show spermatogenetic stages maturing in a caudo-cephalic and centripetal direction. Sperm ducts join together dorsally to the intestine before opening into a pear-like caudal organ. An unpaired, dorsal ovary lies anteriorly to the confluence of sperm ducts. Oocytes mature in a caudo-cephalic direction; no oviduct nor female pore is present. The spermatozoa are fusiform, with a very short tail. The anterior end of the sperm is a small, conic hood which corresponds to the acrosome. The following, spindle-shaped corkscrew region contains a nuclear helix surrounding a central axis made of a single, giant mitochondrion. The 9+2 axoneme is enclosed by a bilayered, obliquely striated cylinder only in the proximal tract. The morphology of the reproductive system and spermatozoa of Mesodasys species is discussed, and the hypothesis of hypodermic impregnation in this genus is supported.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received: 20 November 1998 / Accepted: 6 July 1999
Rights and permissions
About this article
Cite this article
Fregni, E., Balsamo, M. & Ferraguti, M. Morphology of the reproductive system and spermatozoa of Mesodasys adenotubulatus (Gastrotricha: Macrodasyida). Marine Biology 135, 515–520 (1999). https://doi.org/10.1007/s002270050652
Issue Date:
DOI: https://doi.org/10.1007/s002270050652