Healy, J.M. and Jamieson, B.G.M.
1989e. An ultrastructural study of spermatozoa of Helix aspersa
and Helix pomatia (Gastropoda, Pulmonata). Journal of
Molluscan Studies 55, 389-404.
Spermatozoa of the pulmonates Helix aspersa
Muller and H. pomatia Linnaeus
are examined in detail using
electron microscopy (TEM). Important features such as the acrosome,
sheath, nucleus and terminal region of the midpiece are described for
time. Also presented are the first ultrastuctural observations on
from spermatopheres in any pulmonate gastropod (H. aspersa). No
differences could be found between sperm taken from spermatophores and
within the hermaphrodite duct in H.
aspersa. Spermatozoa of H.
and H. pomatia show all the
characteristics of euthyneuran spermatozoa,
helically-keeled nucleus; distinctive arrangement of acrosomal
(apical vesicle, acrosomal pedestal), and extremely elongated midpiece
and glycogen helix enclosed by matrix and paracrystalline layers). The
nucleus of both species is short, and the midpiece also forms the
portion of the spermatozoon (glycogen piece absent). The extraordinary
positioning of the acrosome in H.
apex-is not observed in H. pomatia,
though a perinuclear sheath
another acrosomal component) is present in sperm of both species. Helix
spermatozoa are compared with other euthyneuran sperm and
from the systematic viewpoint.